Hate ^allege of JVgricultutc
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Cornell University Library
TN 775.R55 1896
Aluminium; its history, occ"''* "SiPmSP^
3 1924 003 633 751
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ALUMINIUM.
ALUMINIUM:
ITS HISTORY, OCCURRENCE, PROPERTIES,
METALLURGY AND APPLICATIONS,
INCLUDING ITS ALLOYS.
BY
JOSEPH W. RICHARDS, A. C, Ph.D.,
INSTRUCTOR IN METALLURGY AT THE LEHIGH UNIVERSITY.
\
THIRD EDITION,
REVISED AND ENLARGED.
ILLUSTKATED BY
f . .
FORTY-FOUR ENGRAVINGS AND TWO DIAGRAMS.
PHILADELPHIA :
HENRY CAREY BAIRD & CO.,
INDUSTRIAL PUBLISHERS, BOOKSELLERSi, AND IMPORTERS,
No. 810 Walnut Stbebt.
LONDON :
SAMPSON LOW, MARSTON & CO., Limited,
ST, dunstan's house, petteb lane, fleet stbeet,
1896,
TH115'
(5 13% S^
COPYEiaHT BY
JOSEPH W. RICHARDS,
1895.
Feinted by the
WICKEESHAM PRINTING CO.,
63 and 55 N. Queen Street,
Lancastek, Pa., U. S. A.
l>e&icatlon.
TO THE MEMORY OF
iFteberick Mobler
OP
GOTTINGEN,
THE DISCOVERER OP ALUMINIUM,
AND OF
Ibenti Sainte^Claite Seville
OF
PARIS,
FOUNDER OP THE ALUMINHJM INDUSTRY.
THE FRUITS OF WHOSE LABOBS
HAVE ENBICHED SCIENCE AND BENEFITED MANKIND.
PREFACE TO THE THIRD EDITION.
Ten years ago aluminium was an almost unknown metal;
then it sold for twelve dollars a pound, now it is bought for fifty-
cents ; then the yearly production was less than is the present
daily output ; then only three books had been written about it,
since then seven have appeared and two journals have been es-
tabHshed to represent it. The lowering of the price, the increased
production, the wide circulation of reliable information about
aluminium, have brought to pass the dream of Deville, for it has
truly become a metal of every-day life.
The abundance of aluminium in nature, the purity of its ores,
its wonderful lightness and adaptability to numerous purposes,
indicate that the goal of the aluminium industry will be reached
only when this metal ranks next to iron in its usefulness to man-
kind.
To assist this consummation by furnishing all the reliable in-
formation about aluminium, to thus enlighten the general reader,
help the workman, instruct the student, assist the experimenter,
and in every way to speed the industry on its destined path,
is the raison d'etre of this work.
The writer thanks the public for its generous appreciation of
his past endeavors. The volume has been revised to date, sev-
eral chapters have been largely re-written, and every effort has
been made to make the work worthy of the splendid industry
which it represents.
Joseph William Richards.
The LEfflGH University,
Bethlehem, Pa., October zj, iSgs-
(vii)
PREFACE TO THE SECOND EDITION.
If it was true that no apology was necessary in presenting a
work on Aluminium in English, as stated in the preface to the
first edition of this book, it is equally true that still less apology
is necessary in offering an improvement on that work.
The present volume is designed to be an improvement on
the former one in the following respects : Mistakes have been
corrected wherever detected by the author or pointed out by
his friends ; in some instances the order of treatment of different
parts has been revised, so as to bring them into strict, logical
sequence ; the more strictly historical processes are described in
greater detail, in order to preserve a complete record of the rise
of the aluminium industry; chapters have been added treating
on the properties and the preparation of aluminium compounds,
on the theoretical aspect of the reduction of aluminium com-
pounds, and on the analysis of commercial, aluminium and its
common alloys ; the original chapters have been in several cases
sub-divided, and every part treated more by itself and in greater
detail than before ; finally, additions have been made through-
out recording and describing the progress achieved in the last
three years, with a completeness which it is hoped is up to the
standard of the rest of the book.
The method of treatment in the present edition will be found
to be more critical, for wherever a reasonable doubt might be
expressed as to the correctness of certain claims, or a rational
explanation advanced for certain phenomena, the author has not
(ix)
X PREFACE TO THE SECOND EDITION.
hesitated to put his best thought on the question and to state
his conclusions unreservedly.
The friendly criticisms of the scientific press and their sug-
gestions have been kept in view in preparing this new edition.
The spelHng " aluminium " has been retained, because no suffi-
cient reasons have been advanced for changing it to " alu-
minum;" and even if each way was equally old and as well-
sanctioned by usage and analogy as the other, the author's
choice would be the longer spelling, as being more euphonious
and agreeable to the ear.
It has been the author's endeavor to make this volume as
complete as possible, as accurate as possible, to write it in a
manner which will be entertaining to the general reader, and to
furnish a treatise which will be of practical value to the practical
metallurgist, as well as of scientific merit where it touches on
matters of theory.
J. W. R.
Bethlehem, Pa., March 12, i8()o.
PREFACE TO THE FIRST EDITION.
No apology is necessary in presenting a work on Aluminium
in English. In 1858 Tissier Bros, published in France a small
book on the subject. H. St. Claire Deville, the originator of
the aluminium industry, published a treatise, also in French, in
1859. Deville's book is still the standard on the subject. Until
December, 1885, we have an intermission, and then a work by
Dr. Mierzinski, forming one of Hartleben's Chemisch-Technische
Bibhothek, which is a fair presentation of the industry up to
about 1883, this being a German contribution. Probably be-
cause the English-speaking people have taken comparatively
little hand in this subject, we find no systematic treatise on
aluminium in our language. The present work aims to present
the subject in its entirety to the English reader.
Tissier, Deville, Mierzinski, and the German, French, and
English scientific periodicals have been freely consulted and
extracted from, full credit being given in each case to the author
or journal. As this art has of late advanced so rapidly, it has
been a special aim to give everything that has been printed up
to the time of publication.
The different parts of the work are arranged in what seemed
their logical order, corresponding closely to that followed by
Deville. The Appendix contains an account of laboratory ex-
periments, etc., several of which, it is trusted, may be of value.
In conclusion, the author wishes to thank the Faculty of his
" Alma Mater," Lehigh University, for their permission to use
(xi)
Xli PREFACE TO THE FIRST EDITION.
his Thesis on Aluminium as the basis of this treatise ; also, to
acknowledge his indebtedness to Dr. Wm. H. Greene, of Phil-
adelphia, for assistance rendered in the preparation of the work
for the press.
J. W. R.
Philadelphia, November 2j, j8S6.
ABBREVIATIONS DSED IN MAKING REFERENCES.
SEPARATE WORKS ON ALUMINIUM
{Arranged chronologically.^
Tissier . Recherche de 1' Aluminium. C. & H. Tis-
sier. Paris : J. Hetzel et Cie. 1858.
Uhlenhuth Die Darstellung des Aluminiums. Ed. Uhl-
enhuth. Quedlinburg: G. Basse. 1858.
Deville De I'Aluminium. H. St. Claire Deville.
Paris : Mallet-Bachelier. 1859.
Mierzinski . Die Fabrikation des Aluminiums. Dr. Stan-
islaus Mierzinski. Vienna : Hartleben's
Chemisch-technische Bibliothek. 1885.
Richards (ist Ed.) Aluminium. Joseph W. Richards. Phila-
delphia : Henry Carey Baird & Co. 1887.
Richards (2nd Ed.) Aluminium. Joseph W. Richards. Phila-
delphia : Henr}' Carey Baird & Co. i8go.
Le Verrier Note sur la Metallurgie de I'Aluminium.
U. LeVerrier. Paris: BaudryetCie. 1891.
Minet L' Aluminium. Adolphe Minet. Paris ; Ber-
nard Tignol. 1892.
Lejeal L'Aluminium. Adolphe Lejeal. Paris: J.
B. Bailli^re et File. 1894.
TREATISES IN ENCYCLOPEDIAS.
Fremy Enclyclop£die Chimique. Fremy. Paris :
Ch. Dunod.
Art : L'Aluminium par Margottet (1883).
Art : L'Aluminium et ses Alliages par Wick-
ersheimer (1890).
Kerl and Stohman Enclyclopadisches Handbuch der Tech-
nischen Chemie. 4th Ed. Brunswick :
Vieweg und Sohn. 1886.
Art: Aluminium von R. Biederman.
Watts Watts' Dictionary of Chemistry.
( xiii )
xiv ABBREVIATIONS USED IN MAKING REFERENCES.
JOURNALS AND PERIODICALS.
Ann. de Chim. et de Phys. . . Annales de Chimie et de Physique.
Ann. der Chem. und Pharm. ) Liebig's Annalen der Chemie und Phar-
Liebig's Ann J made.
Bull, de la Soc. Chim Bulletin de la Soci^t^ Chimique de Paris.
Chem. News The Chemical News.
Chem. Zeit. . . Chemiker Zeitung (Cothen).
Compt. Rend Comptes Rendus de les Stances de I'Acadd-
mie. Paris,
Dingl. Jrnl Dingler's Polytechnisches Journal.
E. and M. J The Engineering and Mining Journal.
Jahresb. der Chem Jahresbericht ueber die Fortschritte der
Chemie.
Jrnl. Chem. Soc Journal of the Chemical Society.
Jrnl. der Pharm Journal der Pharmacie.
Jrnl. fiir pr. Chem Erdmann's Journal fiir praktische Chemie.
Mon. Scientif. Le Moniteur Scientifique. Dr. Quesnesville.
Phil, Mag The London and Edinburgh Philosophical
Magazine.
Phil. Trans ... Transactions of the Royal Philosophical
Society.
Pogg. Ann Poggendorff's Annalen.
Poly. Centr. Blatt Polytechnisches Central-Blatt.
Proc. Ac. Nat. Sci. .... Proceedings of the Academy of Natural
Sciences (Philadelphia).
Quarterly Journal Quarterly Journal of the Society of Arts.
Rpt. Brit. A. A. S Report of the British Association for the
Advancement of Science.
Sci. Am. (Suppl.) Scientific American (Supplement).
Wagner's Jahresb Wagner's Jahresbericht der Chemischen
Technologic.
Zeit. fiir anal. Chem Zeitschrift fiir Analytische Chemie.
JOURNALS REPRESENTING THE ALUMINIUM INDUSTRY.
The Aluminum World .... New York. Published monthly. Estab-
lished September, 1894.
L'Aluminium Paris. Published monthly. Established
January, 1895.
CONTENTS.
CHAPTER I.
History op Ai<uminium.
'page
The alumen of Pliny; Alumen Roccae or rock alum; Alums and vitriols
confounded .... ....... 1
Paracelsus distinguishes alums from vitriols; Views of Ettmiiller, Stahl,
Hoffman, Geoffroy, Hellot and Pott, on the nature of the base of
alum; Marggraff's dissertations on alum and its earth; Morveau fixes
the nomenclature of alumina 2
The search for aluminium; Macquer's supposition; Baron's attempts to
reduce alumina; Lavoisier's views on the nature of alumina . . 3
Ruprecht and Tondi's experiments; Criticisms of Savaresi, Klaproth
and Karsten; Dr. Hare melts alumina without noticing any reduction;
Sir Humphry Davy attacks the earths with his great battery . . 4
Davy's experiments on reducing alumina; He reduces it in the electric
arc in presence of iron; He suggests a name for the metal ... 5
Prof. Benjamin Silliman's experiment with Dr. Hare's blow-pipe; Oer-
sted's attempt to reduce aluminium chloride; Berzelius' attempt to
reduce cryolite 6
Professor Frederick Wohler, of Gottingen, isolates aluminium as a
metallic powder, in 1827 7
Wohler obtains the metal in globules, in 1845; Professor Henri Saint-
Claire Deville obtains aluminium en masse, in 1854 . ... .8
Deville's first attempts; His paper read before the French Academy on
February 6, 1854 . . 9
The Academy aids Deville in his further work ; A reclamation by
Chenot; Further experiments at the Ec61e Normale; Reduction of
aluminium chloride by the battery 10
Deville's experiments in manufacturing sodium; Installation of the
sodium process at Rousseau Bros, chemical works at La Glaci^re;
Deville and Bunsen publish their electrolytic methods; The Emperor
Napoleon III. becomes interested and defrays the expense of further
experiments H
(XV)
xvi CONTENTS.
PAGE
TheTissier Bros, experiment on producing sodium; Deville's work at
Javel; The industry on a firm basis ' ^^
Exhibit of aluminium at the Paris Exposition, 1855; Misunderstanding
between Deville and the Tissier Bros 13
Tissier Bros, start an aluminium works near Rouen; History of this
14.
enterprise ^^
Deville and his friends put up a large plant at La Glaci&re; Removal to
Nanterre; Removal to Pechiney and Co.'s works at Salindres; Tissier
Bros, publish their "Recherchessurl'Aluminium" {1858) . . 15
Deville publishes his "De I'Aluminium" (1859); Hi^ conclusions as to
the usefulness of aluminium 16
Experiments of Dr. Percy and H. Rose on reducing cryolite; Manufac-
ture of aluminium by A. Monnier, of Camden, N. J.; Calculation of
cost of the new metal by W. J. Taylor 17
The first aluminium works in England, at Battersea (1858); Bell Bros,
works near Newcastle-on-Tyne; Project to start works at Berlin; Dr.
Clemens Winckler's retrospect, 1879 18
Condition of the aluminium industry in 1879 19
The industry from 1879 to 1882; W. Weldon's views on its prospects in
1883 . 20
The search for a substitute for sodium ; Webster's improvements in the
industry .21
H. Y. Castner's invention for producing sodium; His experiments in
New York 22
Castner's demonstration in England; Unites with Webster to form the
"Aluminium Company, Limited; " Large works at Oldbury near Bir-
mingham, stop making aluminium in 1891 ...... 28
Revival of electric methods, using dynamos instead of the battery;
Gratzel's process 24
Kleiner's process; Hall's process, invented in 1886, essentially different
in principle from previous attempts 25
Incorporation of the Pittsburgh Reduction Co. to work Hall's process;
Works at Kensington, Pa., and Niagara Falls; Minet's experiments
at Creil and works at Saint Michel, Savoy 26
The electric-furnace methods; Siemens furnace; Grabau's experiments;
Mierzinski's remarks 27
Cowles Bros, process, 1885; Plant at Lockport, N. Y., and works in
England; The principle of the process . 28
H^roult's processes; Principle of his alloy process 29
The "Aluminium Industrie Actien Gesellschaft " formed to work
HSroult's processes; Dr. Kiliani, manager of their works at the Falls
of the Rhine; The Hiroult process in France 30
Experiments with H^roult's process in the United States; The "Alliance
Aluminium Co., of London," formed to work Netto's sodium process. 31
Failure of the Alliance Aluminium Co.; Grabau's improvements in pro-
CONTENTS. xvii
PAGE
ducing sodium and aluminium fluoride; Colonel Frishmuth's works
in Philadelphia 32
Exhibit of aluminium at the Paris Exposition, 1889; Progress of the in-
dustry since 1890 33
The Cowles Electric Smelting Co. sued for infringement of the Hall
process; Exhibits of aluminium at the Columbian Exposition in Chi-
cago, 1893; The production of aluminium one of the great achieve-
ments of the century 34
Statistics; The decline in the price of aluminium and aluminium bronze. 35
Production of aluminium in France from 1854 to 1892; Production in
England; In Switzerland 36
Production of the United States from 1883 to 1894; Total aluminium
produced in the world to the end of 1892; World's production in 1893;
An estimate of the production in 1894 37
The probable production in 1895 38
CHAPTER II.
Occurrence of Aluminium in Nature.
Clarke's estimate of the proportion of aluminium in the earth's crust;
Not found metallic; Most frequent combinations in rocks, soils and
clays; Occurrence in some plants; Ricciardi's experiments on the
assimilation of alumina by plants 39
Composition of the most frequent aluminium minerals; Bauxite the
most useful mineral for the aluminium industry 40
Localities in which bauxite occurs ; Deposits worked in the United
States; Value per ton 41
Analyses of foreign bauxites 42
Analyses of American bauxites 43
Laur's generalizations concerning French bauxites . . . .44
Hunt's generalizations on American bauxites; The occurrence of cryo-
lite in Greenland 45
Composition of cryolite; Amount imported into the United States; De-
scription of a small deposit in Colorado 46
Analysis of the Colorado cryolite; The sources of corundum . . 47
Mining of corundum in the United States; The composition and proper-
ties of kaolin 48
Localities of the large kaolin beds; Value of kaolin as an aluminium
ore; Common clays 49
Native sulphate of alumina; Deposits in New Mexico, Colorado and
Ohio 50
Economic value of the aluminium sulphate deposits . . . .51
xvni CONTENTS.
CHAPTER III.
Physicai, Properties of Ai,uminium.
PAGE
Commercial aluminium not chemically pure; The most frequent im-
purities 52
The influence of small amounts of impurities on the physical properties
of the metal 53
Analyses of commercial aluminium ; Notes on the analyses . . .54
Recent analyses of present commercial metal 55
Difference in the composition of metal made by the sodium and the
electrolytic methods; The different conditions in which silicon exists
in aluminium; Rammelsberg's analyses ...... 56
Absorption of gases by molten aluminium; Dumas' analyses; Author's
observations; Tie Verrier's detection of carbon in commercial alumin-
ium . ..... 57
Influence of carbon on the physical properties of aluminium; Le Ver-
rier detects nitrogen in commercial aluminium ... .58
Influence of nitrogen on the physical properties of aluminium; The
color of pure and impure aluminium ....... 59
Tarnishing of aluminium in the air; Fracture of purest aluminium . 60
Fracture of impure ahiminium; Hardness; Testing quality -with the
knife; Hardening by cold working .61
Comparison of the hardness of aluminium with other metals; Specific
gravity . 62
Influence of impurities on the specific gravity; Increase of specific
gravity by working . . ....... 63
Comparison of the specific gravity of aluminium and other metals . 64
Comparative value of equal weights and equal volumes of the different
metals; Fusibility 65
Melting point determined by the electric pyrometer; Influence of im-
purities on the melting point; Volatilization; Odor .... 66
Taste; Magnetism; Sonorousness 67
Sound produced by an aluminium bell, bar and tuning-fork; Alumin-
ium sounding boards 68
Velocity of sound in aluminium; Crystalline form; Elasticity . . 69
Tensile and compressive strength ........ 70
Table of tensile tests . . 71
Table of compressive tests; Transverse tests . . . . 72
General conclusions of Messrs. Hunt, Langley and Hall; Variation of
tensile strength with the temperature 73
Influence of working and annealing on the mechanical properties;
Tensile strength in comparison with weight 74
Comparison of the tensile strength with that of other metals, section
for section and weight for weight; Malleability . ... 75
CONTENTS. XIX
PASE
Thickness of aluminium leaf; Color by transmitted light; Ductility . 76
Expansion by heat; Specific heat 77
Determinations of the specific heat by Regnault, Kopp, Mallet, Tom-
linson, Naccari, Le Verrier 78
Specific heat and latent heat of fusion as determined by Pionchon and
the author 79
The amount of heat in molten aluminium; Agreement with Dulong
and Petit's law 80
Slow melting of aluminium due to its great latent heat of fusion; Com-
parison with other metals; Electric conductivity ..... 81
Professor Dewar's determinations of the electric conductivity at very
low temperatures; Conductivity for heat ...... 82
CHAPTER IV.
Chemical Properties of Aluminium.
Atomic weight; Action of air . . . . , . . . .83
Resistance to air when melted; Action of air and water together;
Piqures 84
Combustion of aluminium powder or leaf ; Action of water . . .85
Decomposition of water by aluminium leaf; Action of hydrogen sul-
phide and sulphur 86
Experiment of the author with hydrogen sulphide and molten alu-
minium . 87
Action of sulphuric acid; Ditte's explanations 88
Le Roy's quantitative tests with sulphuric acid 89
Action of nitric acid; Ditte's observations 90
Experiments of Le Roy, Lunge and the author on the action of nitric
acid; Use of aluminium in the Grove battery; Action of hydrochloric
acid ... .91
Action of hydrobromic, hydriodic and hydrofluoric acids; Experiment
by the author; Action of organic acids, vinegar, etc 92
Action of the acids found in food; Deville's prediction of the usefulness
of aluminium for culinary utensils; Lubbert and Roscher's experi-
ments with thin foil 93
Balland's exhaustive tests with foods ; Rupp's results; Lunge and
Schmid's experiments 94
Details of Lunge and Schmid's tests 95
Conclusions from these tests; Confirmation of these results by actual
experience of two years with aluminium culinary utensils . . -96
Action of common salt, molten and in solution; Sea- water; Aluminium
boats ■ ^'^
CONTENTS.
PAGE
Action of organic secretions, the saliva, etc 98
Action of caustic potash, caustic soda; Quantitative tests . . .99
Action of ammonia; Lime water; Solutions of metallic salts . . . 100
Action of solutions of mercury, copper, silver, lead .... 101
Action of solutions of zinc, alkaline chlorides, aluminium salts; Action
of melted fluorspar; Use as a flux 102
Use of cryolite as a flux; Action of molten silicates and borates . . 103
Action of fused nitre; Purification of impure aluminium by nitre; Re-
action with alkaline sulphates and carbonates 104
Reaction of aluminium on oxides of manganese, zinc, iron, lead, copper,
barium 105
Greene and Wahl's process of producing pure manganese; Action of
phosphate of lime, silver chloride, mercurous chloride, carbonic oxide,
hydrogen, chlorine, bromine, iodine, fluorine 106
CHAPTER V.
Properties and Preparation of Aluminium Compounds.
General considerations; Position of aluminium in the periodic classifi-
cation of the elements . 107
Observations on the structure of aluminium compounds . . . 108
The tri-valency of aluminium ; Aluminates ...... 109
Neutral salts of aluminium; Basic salts; General methods of formation
of aluminium salts ... 110
General properties of aluminium salts; Chemical reactions in solution;
Reactions before the blowpipe Ill
Alumiuium oxide; Physical and chemical properties . . . .112
Hydrous aluminium oxides, natural and artificial; The soluble hydrate. 113
Aluminates; Potassium aluminate; Sodium aluminates; Barium alumi-
nate ...... 114
Aluminates of calcium, zinc, copper, magnesium, iron, beryllium; Alu-
minium chloride 115
Hydrous aluminium chloride; aluminium-sodium chloride . . .116
Double chlorides of aluminium with phosphorus, sulphur, selenium,
ammonium 117
Aluminium-chlor-sulphydride ; Aluminium-chlor-phosphydride ; Alu-
minium bromide; Aluminium iodide 118
Aluminium fluoride; Methods of production 119
Fluorhydrate of aluminium; Aluminium-hydrogen fluoride; Alumin-
ium-sodium fluoride .120
Aluminium sulphide; Double sulphides with sodium and potassium . 121
Use of aluminium sulphide in the laboratory for generating hydrogen
sulphide; Aluminium selenide; Aluminium borides . . . .122
CONTENTS. xxi
PAGE
Aluminium boro-carbides; Aluminium carbide 123
Production of aluminium carbide in the electric furnace by Le Verrier . 124
Composition and properties of aluminium carbide; Aluminium nitride 125
Aluminium sulphates, anhydrous and hydrous 126
Basic aluminium sulphates 127
Alums; Potash alum; Ammonia alum .... . . 128
Soda alum; Bouble sulphates of aluminium and the metals; Aluminium
selenites 129
Aluminium nitrate; Aluminium antimonate; Aluminium phosphates . 130
Aluminium carbonate; Aluminium borate 131
Hydrous aluminium borates; Aluminium silicates; Blast furnace slags 132
CHAPTER VI.
Preparation of Aluminium Compounds for Reduction.
The preparation of alumina; Preparation from alums or aluminium sul-
phate .... .133
Preparation of alumina from ammonia alum ...... 134
Method used by Deville at Javel; Tilghman's method . . . 135
Webster's process of making alumina from potash alum . . 136
Preparation of alumina from bauxite ; Method uSed at Salindres . . 137
Heating with soda and washing out the aluminate ... . 138
Apparatus used for washing; Precipitation of alumina by carbonic acid
gas 139
Apparatus used for the precipitation ; The barattes . . . 140
Washing and drying the precipitated alumina; Behnke's method of
treating bauxite; Lieberfs method 141
Muller's method for extracting alumina from silicates; Use of common
salt to decompose bauxite; Wagner's method of treating bauxite . 142
Laur's method of using sodium sulphate to decompose bauxite; Lowig's
experiments on precipitating alumina from sodium aluminate solu-
tion; Dr. Bayer's improvements . 143
Preparation of alumina from cryolite; The dry way .... 144
Furnace for heating cryolite with chalk; Thomson's method . . 145
Conduct of the operation ; Washing the fusion .... 146
Production of the carbonic acid gas for precipitation .... 147
Composition of the precipitate; Action of steam on molten cryolite;
Utilization of aluminous fluoride slags 148
Utilization of the residual slags from sodium retorts by fusing with the
aluminous slags; Decomposition of cryolite in the wet way . . 149
Method used by Deville at Javel; Modification of this process by Sauer-
wein ............. 150
Reactions in Sauerwein's process; Weber's method of decomposing
cryolite; Schuch's reaction 151
xxii CONTENTS.
Preparation of aluminium chloride and aluminium-sodium chloride . 152
Method used by Beville on a small scale at Javel . . . 1 53
Manufacture by Deville on a large scale 154
Furnace used and working of the operation . . . 155
Output of the furnace; Purification of the crude chloride . . .156
Deville's idea of making the double chloride; Margottet's description
of the apparatus used at Salindres . ... 157
Conduct of the operation at Salindres . . . . . 158
Cost of making the double chloride at Salindres . . . 159
Plant of the Aluminium Company, Limited, at Oldbury, near Birming-
ham, England . . . . _. . . 160
Arrangements of the furnaces and conduct of the operation . . .161
Output of this plant; Purity of the double chloride . .162
Castner's method of purifying the double chloride . ... 163
Cost of the purified double chloride; Gadsden's method of producing
aluminium chloride; Count R. de Montgelas' improvement . . 164
Prof. Mabery's process for producing aluminium chloride in the electric
furnace; Curie's method; Warren's general process for anhydrous
metallic chlorides . . ... 165
Camille A. Paure's process; Description by Berthelot . 166
Details of Faure's process; Output claimed; DuUo's method of making
aluminium chloride from clay ... ... 167
Remarks on Dullo's suggestions; The preparation of aluminium fluoride
and artificial cryolite . ....... 168
Berzelius' method of making artificial cryolite; Deville's methods . 169
Pieper's reactions in the wet way; Bruner, Deville and Hautefeuille on
making aluminium fluoride . . . . 170
Grabau's processes; Aluminium fluoride from aluminium sulphate and
fluorspar . . ... ... 171
Aluminium fluoride indirectly and directly from kaolin . . . 172
Precautions necessary to obtain it free from iron 173
The preparation of aluminium sulphide; Fremy's researches . . . 174
Purity of the aluminium sulphide produced .... . 175
Reichel's results; Experiments of the author . .... 176
Propositions of Comenge, Petitjean, etc. . . • 177
Lauterborn's patent anticipated . .... 178
CHAPTER VII.
The Manufacture of Sodium.
Relations of the production of sodium to the aluminium industry; Isola-
tion of sodium by Davy, Gay Lussac and Thenard, Curaudau . . 179
Briinner's apparatus; Donny and Mareska's condenser; Deville's im-
provements at Javel (1855) . ]80
183
184
185
186
187
188
189
190
191
CONTENTS. xxiii
PAGE
The chemical and physical properties of sodium . ... 181
Method of reduction used at Javel; Composition of the mixtures for re-
duction .... .... ... 182
Utility of the different ingredients of the mixtures; Difficulties of con
densing sodium vapor . .
Mixture used at La Glacifere and Nanterre; Charging the apparatus
Description of retorts and condensers ; Manufacture in mercury
bottles ... . .
The furnace used for manufacture in mercury bottles
Detailed description of condensers
Conduct of the operation . . ...
Handling of the condensed sodium; The temperature necessary for re
ductiou ... ....
Use of decarburized, cast-iron bottles; The continuous manufacture in
cylinders
Furnace for manufacture in cylinders
Arrangement of the cylinders in the furnace 192
Charging and discharging the cylinders . .... 193
Tissier Bros. ' method of procedure at Rouen 194
Furnace used by Tissier Bros ... 195
Charging and discharging Tissier's furnace 196
Causes of loss of sodium; Deville's improvements at La GlaciSre (1857) 197
Deville's large cylinder furnace; Difficulties in its operation . . 198
Deville's attempts to use cast-iron retorts; Deville's improvements at
Nanterre (1859) ... . . ... 199
Necessity of protecting the iron cylinders; Deville returns to smaller
apparatus ... . 200
Cost of sodium at Salindres in 1872; An experiment of Deville's in 1864;
Wagner's method of preserving sodium .... . 201
Reduction of potassium and sodium compounds together; Thompson
and White's method . ... ... 202
Blackmore's process of reducing carbonate of soda; Thowless' ap-
paratus; Jarvis' device for using fire-clay apparatus; Castner's process 203
History and principle of Castner's invention 204
Reaction on which the process is based; Form of furnace used . 206
Experimental furnace erected in England
Conduct of the operation in this furnace .
Yield of the furnace; Composition of the residues .
Cost of sodium by the Castner process
Erection of large works to operate the Castner process
Description of the largest furnaces ....
Manner of working and output of these furnaces
Preservation of the sodium; Reactions in the process
Netto's sodium process; The Alliance Aluminium Company
Details of Netto's apparatus
207
208
210
211
212
213
214
215
217
218
xxiv CONTENTS.
PAGE
Reduction of sodium compounds b3' electricity; Jablochaff's apparatus;
Roger's method 219
Details of Roger's experiments ... 220
Grabau's observations on the electrolysis of molten sodium chloride . 222
Details of Grabau's electrolytic process; Castner's process of electrolyz-
ing caustic soda .... 223
CHAPTER VIII.
Thb Reduction of Aluminium Compounds from the Standpoint of
Thermai, Chemistry.
The proper way to use the data of thermo-chemistry .... 226
Critical temperatures below which reactions do not occur . . . 227
Influence of physical state in determining a reaction; The heat of forma-
tion of some aluminium compounds ...... 228
The heat of formation of alumina compared with that of other oxides;
Elements which reduce alumina easily ..... 229
Possibilities of the reduction of alumina ....... 230
Reduction of alumina by carbon; Necessary conditions to be fulfilled . 231
Heats of formation of chloride, bromide and iodide of aluminium, and
other metals 232
Deductions as to the agents capable of reducing these aluminium salts 233
Heat of formation of aluminium fluoride and other metallic fluorides . 234
Observations on the reduction of aluminium fluoride; Heat of formation
of aluminium sulphide and other metallic sulphides . . . 235
Observations on the reduction of aluminium sulphide; Electricity as a
reducing agent ... 236
The voltage necessary to produce decomposition of metallic fluorides,
chlorides, oxides and sulphides; Tabular view of these data; Observa-
tions thereon ... ...... 237
Electrolysis of baths containing several ingredients; Illustration from
Hall's process ... . 938
Illustration from Minet's process; The voltage required to decompose
alumina at different temperatures . 239
Calculation of the temperature at which hydrogen can begin to reduce
alumina; The same calculation for carbon . . . 240
Alumina has been reduced by carbon in an iron blast furnace; Peculiar-
ity of acetylene gas as a reducing agent . . ... 241
Thermal aspect of other reactions used in the aluminium industry; The
production of aluminium chloride from alumina ..... 242
The production of aluminium sulphide from alumina; Peculiarity of
carbon bi-sulphide from a thermal standpoint • . . . . 244
CONTENTS.
CHAPTER IX.
Reduction op Aluminium Compounds by Means of Potassium or
Sodium.
PAGE
Classification of methods ; The reduction of chlorine compounds ;
Oersted's experiments (1824) 246
Wohler's experiments (1827); Wohler was repeating Oersted's work. 247
Wohler isolates aluminium as a metallic powder ; His experiments
in 1845 . 248
Globules of aluminium obtained by Wohler in 1845 . . . 249
Impurity of Wohler's metal; Deville's experiments in 1854 . 250
Deville obtains pure aluminium in ingots ...... 251
Deville's methods devised in his laboratory and applied at Javel (1855). 252
Details of the apparatus employed; Conduct of the operation 253
Deville's dissatisfaction with this apparatus and its results . . 255
Deville reduces aluminium chloride by sodium vapor . . . 256
Deville's perfected process as used at Nanterre (1859) ■ • • ^^'^
Details of Deville's improvements . . 258
Reduction in crucibles; Lining of crucibles ...... 259
Reduction on the bed of a reverberatory furnace . ... 261
Deville's views on the aluminium industry in 1859 . . 263
The Deville process as operated at Salindres in 1882 . . . 264
The chemical reactions in the process ... . 265
Description of furnace used and mode of operation . . . 266
Cost of aluminium at Salindres; Niewerth's process . . 268
Gadsden's sodium vapor process; Frishmuth's claims . . . 269
H. von Groussillier's improvement; The Deville-Castner process . 270
Description of Castner's works; Conduct of the operations . . . 271
Efficiency of the process; Closing of these works ... . 273
CHAPTER X.
REDUCTION OF Aluminium Compounds by Means of Potassium or
Sodium {Continued).
Methods based on the reduction of cryolite; Experiments of H. Rose
(1855) .... 274
Experiments of Percy and Dick (1855)
Deville's methods (1856-8) . . .
Tissier Bros', methods; Impurity of the metal
Wohler's improvements on Tissier's method; Gerhard's furnace
Thompson and White's patent; Hampe's experiment; Netto's experi-
ments at Krupp's works at Essen ... .... 290
288
285
287
289
XXVI CONTENTS.
PAGE
Formation of the Alliance Aluminium Co. to work Netto's process . 291
Description of Netto's processes as actually carried out .... 292
Return from Netto's process; The apparatus used at Essen . . 293
Netto's other devices; Failure of the Alliance Aluminium Co. ; Grabau's
process (1887) 294
Advantages of Grabau's method of reducing aluminium fluoride . 295
Reactions in Grabau's process; Description of the operation . . 296
Description of the furnace and apparatus used ..... 297
Great purity of the aluminium produced by Grabau .... 299
CHAPTER XI.
Reduction of Aluminium Compounds by the Use of Ei<ectricity.
Preliminary observations on the laws of electrolysis . . . 301
Calculation of the voltage necessary to decompose aluminium com-
pounds . . . . . . . . 302
Utilization of such calculations; Electrolysis of aqueous solutions 303
Electrolysis using a soluble anode .... ... 304
Electrolysis using insoluble anodes . 305
Electrolysis of baths containing several compounds .... 306
Deposition of aluminium from aqueous solution; Thomas and Tilly's
patent . . 307
Corbelli's process; Thompson's claims; Gore's experiments . . . 308
Dr. Gore's error; Jeangon's process 309
Successful plating by the Harvey Filley Plating Co., of Philadelphia;
Bertrand's assertion; Braun's methods ....... 310
Dr. Fischer's experience with Braun's method; Farmer's apparatus;
Senet's process ; Frishmuth's plating ; Overbeck and Niewerth's
patent . . ... .311
Reinbold's recipe; Count R. de Montgelas' patents . 312
A. Walker's methods of procedure . ... . . 313
Bull's proposition; Burghardt and Twining's patents .... 314
Patents of Gerhard and Smith; Taylor and Coulson; Experience of
Sprague, Dr. Winckler and Dr. Gore 3I5
Opinions of Dr. Mierzinski, Hampe and Watt; Experiments of Dr.
Lisle; Aluminium plating on the Philadelphia Public Buildings . 316
Aluminium plating by Mr. Darling at the Tacony Metal Co. 's works,
Philadelphia gjy
Non-aqueous electric processes; Difficulty of a satisfactory classification. 318
Davy's experiments (1810); Duvivier's experiment (1854) . . .319
Bunsen's and Deville's methods (1854) ... . . 320
Details of Deville's apparatus 32i
Details of Bunsen's apparatus . . .... 322
CONTENTS.
Deville and Caron's method of plating aluminium on copper . . 323
Deville's experiments not an anticipation of Hall's process; Le Chatel-
lier's patent . ... 324
Monckton's proposition; Gaudin's process; Kagensbusch's process . 325
Berthaut's proposition to use dynamos; Gratzel's process . . . 326
Apparatus used by Gratzel; Later modification of his process . . 327
Prof. Fischer's criticism of Gratzel's process; Operation of the process
at Bremen . . .... .... 328
Abandonment of the Gratzel process; Cowles Bros.' process . . . 329
Professor Mabery's description of the Cowles electric furnace . . 330
Dr. T. Sterry Hunt's remarks ... 331
Bradley and Crocker's form of retort used by the Cowles Co. . . 382
A. H. Cowles' form of furnace for continuous working; W. P. Thomp-
son's paper on the Cowles process, read in England .... 333
Cowles Bros', plant at Lockport, N. Y.; Details of the furnaces . . 334
Charging the furnaces . 335
Details of the operation of Cowles' furnaces 336
The enlarged plant at Lockport . 339
The Cowles Syndicate Co.'s works at Stoke-on-Trent, England . . 340
Analyses of Cowles Bros', aluminium bronze 341
Analyses of ferro-aluminium and slags . 342
The reactions in Cowles Bros', process 343
Electrolysis necessarily a secondary factor in the operation of these
furnaces .... 344
H. T. Dagger's experiment with the alternating current in a Cowles'
furnace ....... .... 345
History of the suit — Pittsburgh Reduction Co. vs. Cowles Electric
Smelting and Aluminium Co. 346
Menges' patent; Farmer's process; Kleiner's process . . 347
Kleiner's experiments at Schafthauseu ; Experimental plant in
England 348
Dr. Gore's report on Kleiner's process 349
Output of aluminium by this process; Purity of the metal . . . 352
Kleiner's process outclassed by later processes; Lossier's proposition to
decompose natural silicates of aluminium
Omholt's furnace; Minet's process .
Apparatus used in Minet's process .
Composition and properties of the baths .
Minet's views on the reactions in his baths
Electrical measurements on Minet's pots
Separation of iron and silicon by a carefully regulated current . . 360
Output and quality of aluminium; Installations of this process . . 361
Minet's plant now working on the Hall process; Feldman's process . 362
Uselessness of Feldman's methods; Warren's experiments . . .363
Zdziarski's patent; Grabau's apparatus 364
353
364
355
357
358
359
xxviii CONTENTS.
PAGE
Roger's process; Details of experiments ....... 365
Dr. Hampe on the electrolysis of cryolite . . ... 368
History of Hall's experiments; Interference with H^roult in the United
States patent ofi&ce . ... .... 373
Specifications and claims of Hall's patents 374
Installation of Hall's process at Pittsburgh 376
Conduct of the operation in Hall's pots 377
Consumption of carbon anodes 378
Alumina used in the process; Efficiency of the electrolysis . . . 379
Estimate of cost of aluminium by the Hall process in 1889; Enlarge-
ment of the plant in 1890 381
Removal and enlargement of the plant in 1891 ; The Niagara Falls
plant 382
Total output of the Pittsburgh Reduction Co.'s works; Efficiency of
the process . 383
Chemical reactions in Hall's baths; Alumina is the compound primarily
decomposed ... ...... . 384
Theory of an aluminium oxy-fluoride not proven; Hdroult's processes. 386
Similarity of Hferoult's first process to that of Hall .... 387
HSroult's alloy process; Installation at the Falls of the Rhine . . 388
Description of furnaces used . ....... 389
Conduct of the operation ... 390
Output at full efficiency; Theoretical output ..... 392
H^roult's alloy process not essentially electrolytic in its operation . 393
HSroult's apparatus for pure aluminium .... 394
Recent enlargements at the Rhine Falls ; The Heroult process in
France 395
Hdroult's alloy process at Boonton, N. J 896
Details of cost of pure aluminium atNeuhausen; Faure's electrolytic
process ... 398
Winkler's patent; Willson's crucible 399
Grabau's electrolytic process; Bucherer's patent ..... 400
The Neuhausen sulphide process . 401
CHAPTER XII.
REDUCTION OF Al<UMINIDM COMPOUNDS BY OTHER MEANS THAN SODIUM
OR El,ECTRICITY.
Reduction by carbon without the preseuce of other metals; Chapelle's
attempt ... 402
Reinar's experiment with alum; Thowless' claim . ... 403
Patent of Pearson, Liddon and Pratt; Bessemer's ideas .... 404
Reduction by carbon and carbon dioxide; Morris's claims . . . 405
CONTENTS. xxix
PAGE
Ideas of P. A. Emanuel; Reduction by hydrogen 406
Gerhard's #patent; Success of H. Warren in reducing alumina by
hydrogen 407
Reduction by carburetted hydrogen; Fleury's experiments; Petitjean's
statement 408
Experiments of L^b^deef, Dr. Lisle, R. E. Green 409
Reduction by cyanogen; Knowles' patent; Corbelli's process; Experi-
ments of Deville and Lowthian Bell 410
Reduction by double reaction; Comenge's process; Niewerth's furnace 411
Process of G. A. Faure; Reduction by or in presence of copper; Calvert
and Johnson's experiments ........ 413
Evrard's method of making aluminium bronze; Benzon's patent . 414
Faure's patent .... 415
Experiments by BoUey, List, Dr. Lisle and Hampe . . .416
Experiments of Reichel and the author; Processes of A. Mann and L. Q.
Brin ... . . .... 417
Reduction by or in presence of iron; Experiments of Comenge, Lauter-
born, Reichel and the author; Niewerth's process .... 418
Thompson's method 419
Calvert and Johnson's experiments 420
Chenot's reclamation; Use of spongy iron . . . . 421
Faraday and Stodart's investigations; Wootz steel 422
Presence of aluminium in pig-iron ; Reports by various analysts . . 423
Billings' attempt to reduce alumina in contact with iron; Cleaver's
patent . . ... . . 424
Ostberg's statement about aluminium in pig-iron; Brin Bros.' process . 425
Baldwin's process for treating foundry iron . . . . 426
Alloy of the Williams Aluminium Company; Bamberg's method . . 427
Aluminium in pig-iron from Marshall Bros.' Newport furnace . , 428
Reduction by or in presence of zinc; Statements of Bdk^toff, DuUo,
Basset . ... 429
Wedding's remarks on Basset's process; Experiment by the author . 431
Works of F. J. Seymour at Findlay, Ohio ... . . 432
Lauterborn's method of reduction by zinc . .... 433
Clark's doubtful processes .... ... 434
Dr. Lisle on reducing aluminium sulphide by zinc; Bamberg's patent;
Reduction by lead ... 435
Reduction by manganese; Weldon's claim; Greene and Wahl's observa-
tions t 436
Reduction by magnesium; Gratzel's patent; Roussin's statement; Mont-
gelas' patent; Winkler's experiments on alumina . . . 437
Reduction by antimony; Lauterborn's formulas; Experiment by the
author 438
Reduction by tin; Process of Howard and Hill; Dr. Lisle's successful
experiments . 439
CONTENTS.
PAGE
Reduction by phosphorus; Grabau's process . . ... 440
Reduction by silicon; Wanner's claims «• -441
CHAPTER XIII.
Working in AItItminium.
Melting; Deville's recommendations 442
Biederman's directions; The author's methods . ... 443
Bauxite and magnesite linings for crucibles and furnaces . . 444
Casting; Deville's remarks 445
Casting under pressure . ..... . 446
Aluminium hollow- ware casting; Purification of aluminium; Freeing
from slag . . 447
Freeing from dissolved impurities 449
Removal of zinc by distillation; Test of Buchner's method of purifica-
tion by hydrogen gas . . 450
Purification by other gaseous reagents; Mallet's method of making
chemically pure aluminium 451
Ive Verrier's experiment with alkaline fluoride; Use of sodium to re-
move dissolved gases; Annealing; Hardening 452
Effect of chilling; Rolling; Beating into leaf 453
Rolling into tubes by the Mannesmann process; Very fine tubes made
by Ivins, of Philadelphia; Drawing into wire . . . 454
Stamping and spinning; Grinding, polishing and burnishing . . 455
Special polishes for aluminium; Engraving; Cleaning and pickling;
Mat . . ... 456
Welding by electricity; Soldering; Requirements of a satisfactory
solder; Difficulties peculiar to aluminium . . . . 457
Deville's views on soldering aluminium . . . 458
Mourey's first practical solders . ... ... 459
Bell Bros. ' method of using Mourey's solders ..... 461
Frishmuth's solders; Schlosser's solder for dental work .... 462
Bourbouze's solder of aluminium and tin; Thowless' patent solder . 463
Patents of Sellon and Sauer; Novel's alloys for soldering . . . 464
Land's mechanical method; Aluminium specially prepared for soldering 465
Special fluxes recommended; Roman's solder . . . 466
The "Alsite" solder; The phosphorized solder of Mr. Joseph Richards,
of Philadelphia 467
Success of Richards' phosphorized solder; Methods of using . . . 468
Coating other metals with aluminium; Veneering as practiced by M.
Sevrard . . 469
Dr. Winckler's experience . 470
CONTENTS. xxxi
PAGE
Dr. Gehring's method of aluminizing; Broadwell's process for coating
sheet-iron ...... 471
Plating other metals on aluminium; Gilding and silvering by Mourey
and others 472
Veneering with silver or platinum; Rolling together aluminium and
copper sheet; Wegner and Guhr's methods for electro-plating and
coloring; Neeson's methods; The uses of aluminium . . . .473
The place of aluminium among the useful metals . ... 474
The first articles made of aluminium; Use in the French army . . 475
Recommendations of the German military commission; Use for boats . 476
The yacht " Vendenesse;" The French aluminium torpedo boat . . 477
Explorer Wellman's boats and sledges; The yacht "Defender;" Use for
vehicles and flying machines 478
Use architecturally and for decorations; Suitability for mine cages 479
Use in surgery; Dental plates ... . . . 480
Use for scientific instruments; Captain Gordon's sextant . . .481
Advantages of aluminium for engineering and electrical instruments;
Chemical and bullion balances . . 482
Troemner's assay balances; Use for aluminium for minor coinage . . 483
Advantages and suitability for coinage; Use for chemical apparatus . 484
Use for culinary utensils; Its well-established advantages
Use for table ware; Disadvantages for some articles
Aluminium constructions; Use in the battery
Substitution for lithographic stone; Strecker's directions
Use for flash-light powder; Recipes of Villon and Black
Miscellaneous uses ........
485
486
487
488
489
490
CHAPTER XIV-
Ai,i,OYS OF Aluminium.
General remarks; Methods of making the alloys . . . . 492
Division of the alloys into two classes; Influence of Aluminium on the
color of other metals ... 493
Contraction in alloying; Influence of aluminium on the specific gravity
of other metals . 494
Alloys with copper and iron to be considered separately; Alloys with
antimony 495
Unusual property of one antimony alloy; Roche's unstable alloy . . 496
Aluminium and arsenic; Aluminium and bismuth; Aluminium and
boron . . 497
Aluminium and cadmium; Aluminium and calcium .... 498
Aluminium and chromium; Langley's alloy 499
Aluminium and cobalt; Lejeal's test; Aluminium and gallium . . 500
xxxii CONTENTS.
PAGE
Aluminium and gold; Roberts-Austin's tests; Niirnberg gold; Andrews'
experiments .... ....••• 501
Peculiar properties of the violet alloy discovered by Roberts-Austin . 502
Aluminium and lead; Cupellatiou of aluminium 503
Aluminium in anti-friction and type metal; Aluminium and magnesium. 504
Aluminium and manganese; Cowles' alloy • 505
Aluminium and mercury; Deville's mistake; Simple experiment by the
author; Cailletet's method of amalgamation ..... 506
Joule's electrical experiment; Gmelin's observation; Method of amal-
gamation by Watts; Bailie and Fury's study of the subject . 507
Composition and properties of a definite aluminium amalgam . . 508
Action of air, water, acids and other metals, on aluminium amalgam;
Aluminium and molybdenum ........ 509
Aluminium and nickel; Tissier's tests . ..... 510
I^ejeal's alloy with nickel ; The Pittsburgh Reduction Co.'s alloy;
Aluminium- nickel-copper alloys 511
Alloys of Sauvage, Baudrin, Webster; "Neogen" . . . 512
Webster's patented alloys ... ...... 513
" Lechesue; " Method of production and properties . . 515
Cowles Bros.' "Aluminium Silver" and "Hercules Metal;" Andrew's
alloys; Aluminium and phosphorus ... . . 516
Aluminium and platinum; Aluminium and silicon ; Alloys formed
while melting aluminium in crucibles ...... 517
Influence of silicon on commercial aluminium . . . . 518
Aluminium and selenium; Aluminium and silver ..... 519
Silver alloy for dental plates; " Tiers Argent " 520
Aluminium and sodium; Aluminium and tellurium .... 521
Aluminium and tin; Bourbouze alloy . 522
Decomposition of some aluminium-tin alloys 523
Aluminium deleterious to tin-foil; Heycock and Neville, and Minet, on
the fusing points of aluminium-tin alloys ...... 524
Aluminium and titanium; Wohler's alloy ...... 525
Levy's alloy; Alloy made by the Pittsburgh Reduction Company . . 526
Le Verrier's tests of titanium alloys; Aluminium and tungsten; Tests
by he Verrier .... . ,527
Aluminium and zinc; How zinc crept into some early commercial
aluminium .... . ... . 528
Aluminium hardened by zinc and copper; Use of aluminium in the
galvanizing bath and in Parke's desilverizing process .... 529
Aluminium-zinc-copper alloys; Aluminium brasses 530
Baur and Farmer's aluminium brasses; Tests of Cowles Bros', brasses. 531
Professor Tetmayer's tests of aluminium brasses 532
Richards' bronze .... 533
CONTENTS.
CHAPTER XV.
Ai,uminium-Coppe;r Ai<i,oys.
PAGE
Division into two classes; General properties 534
Melting points; Indications of chemical alloys 535
Alloys containing small amounts of copper . ... 536
Aluminium hardened by copper; Tests of these alloys by Captain
Julien ... 537
Aluminium hardened by German silver; Alloys containing small
amounts of aluminium; Aluminium bronzes ... . 538
History of the aluminium bronzes 539
Constitution of aluminium bronzes; Are they chemical combinations? 540
Morin's arguments to prove that the bronzes are chemical alloys . . 541
Action of small amounts of aluminium on bronze, brass and copper . 542
The reducing action of aluminium on dissolved oxides in molten
metals . 543
Bronzes made from alumina versus those made with metallic alu-
minium 544
Method of preparing the bronzes industrially . .... 545
Influence of impurities in the aluminium or copper on the properties
of the bronzes ...... .... 546
Re-melting the bronzes improves their quality ..... 547
Fluidity of the bronzes when melted; Casting the bronzes . . . 548
Thomas D. West on " Casting Aluminium Bronze " . . 549
Shrinkage of the bronzes in cooling; Color . . £52
Specific gravity of the bronzes; Hardness .... . 553
Transverse and compressive strength ... . 554
Tensile strength; Lechatelier's tests . . . . . 555
Tests of tensile strength by Deville, Strange, at the Watertown Arsenal
and Washington Navy Yard ......... 556
Details of tests of Cowles Bros', bronzes . 557
Diagram showing comparison of the strength of wrought-iron, tool-
steel, and two aluminium bronzes ........ 558
Professor Tetmayer's tests of the strength of the bronzes . . . 559
Diagram showing the variation of strength and ductility of the bronzes
with increasing proportions of aluminium; Le Chatelier's test of the
strength at various temperatures 560
Annealing and hardening the bronzes; Forging, hammering and
rolling -561
Filing, chipping and planing the bronzes 562
Anti-friction qualities of the bronzes 563
Conductivity for heat and electricity; Resistance to corrosion . . 564
Suitability of the bronzes for marine construction, chemical purposes
and statuary . 566
xxxiv CONTENTS.
PAGE
Various uses to which the bronzes are applied; Suitability for heavy
guns . ...
Suitability for propeller blades
Brazing and soldering the bronzes
Silicon-aluminium bronze .
Phosphor-aluminium bronze; Boron-aluminium bronze
567
. 568
. 569
. 570
. 571
CHAPTER XVI.
Aluminium-Iron Ahoys.
Iron in commercial aluminium . . ...... 672
Alloys made by Tissier Bros., Michel, and Calvert and Johnson . . 573
Ferro-aluminium ; Manufacture directly from alumina or from the
metals . . ... . . ■ 574
Aluminium in commercial steel, wrought-iron and pig-iron; Effect of
aluminium on the properties of steel ....... 575
Faraday's experiments with Wootz steel 576
Mitis castings; Use of aluminium in casting soft steel . . . 577
Experiments of Gilchrist and R. W. Bavenport .... 579
Spencer's experiments on casting steels . ..... 580
' ' Steel-aluminium ' ' for use in steel ; Effect of aluminium on wrought-
iron . ... 581
History of the Mitis process 582
Rise and progress of the Mitis process; Raw material used . . . 583
Composition of a melt of mitis metal ; Analyses of mitis castings . . 584
The process of making mitis castings ....... 585
Conduct of the process at the Chester Steel Casting Works . . . 586
Explanation of the action of aluminium in making mitis castings; Ost-
berg's views ..... ..... 587
R. W. Davenport's explanation inadequate . .... 588
The author's explanation of the increased fluidity of the melt . . 589
Why mitis castings are without blow-holes . .... 590
Discussion of Davenport's experiment and Howe's explanation . . 592
Professor Le Verrier's explanation ; Professor Arnold's experiment . 593
Summary of the author's views; Influence of aluminium in the puddling
furnace . . ... 594
Influence of aluminium on cast-iron . ...... 595
Systematic investigation of this subject by Messrs. Keep, Maybery and
Vorce . . .... .... 596
General outline of Keep's tests 597
Effect of aluminium on the solidity of the castings; Does the aluminium
remain in the iron ? 59g
Effect of aluminium on the transverse strength of castings . . . 599
Effect on the elasticity of the castings 600
CONTENTS. XXXV
PAGE
Effect on the grain of the castings 601
General effect of aluminium on the fluidity of cast-iron; Shrinkage . 602
Effect on the hardness of the castings . ... . 603
Practical advantages in pouring the castings; General testimony of ex-
perienced foundrymen . . . .... 604
Rationale of the action of aluminium on cast-iron ... . 605
CHAPTER XVII.
Analysis of Ai,uminium and Aluminium Alloys.
Ingredients to be determined; Qualitative tests to precede the quantita-
tive analysis ... 606
Qualitative blow-pipe tests; The specific gravity as an indication of
purity . ... .... 607
Schulze's test of the purity of commercial aluminium; Determination
of silicon . . . . .... 608
Separation of combined and graphitic silicon 609
Regelsberger's method for dissolving and estimating silicon . . 610
Determination of iron and aluminium .611
Separations of iron from aluminium 613
Determination of lead; Determination of copper; Determination of zinc 614
Determination of tin; Determination of silver; Determination of sodium 615
Determination of chlorine; Detemiination of carbon; Determination of
fluorine . . 616
Determination of titanium; Determination of chromium . . . 617
Analysis of ferro-aluminiums; Difficulty of estimating aluminium prop-
erly; Yates' method of procedure 618
Chancel's separation of iron from aluminium; Peter's modification of
Chancel's separation; Thompson's experience 619
Satisfactory separation of iron from aluminium by potassium cyanide;
Precipitation of iron by tri-methylamine 620
Blair's procedure for separating iron from aluminium . . . 621
Electrolytic separations of iron from aluminium; Classen's method;
Professor Smith's method ... . . . 622
Stead's method of separating iron from aluminium; Analysis of alu-
minium bronzes ... ..... 623
Determination of tin, lead and copper in the bronzes .... 624
Determination of iron, aluminium, zinc, cobalt and nickel . . . 625
Analysis of aluminium-zinc alloy; Analysis of aluminium-tin, alumin-
ium-silver, aluminium-nickel, aluminium-manganese and aluminium-
lead alloys ... 626
General remarks on the usefulness of making qualitative tests prepara-
tory to a quantitative analysis . 627
Index ... ... 629
ALUMINIUM,
CHAPTER I.
HISTORY OF ALUMINIUM.
Pliny* tells us that alumen was the name of several kinds of
salts used in dyeing, a white kind for dyeing bright colors and
a dark kind for dull colors ; that all alumen had an astringent
taste and was colored black by the juice of the pomegranate
(a reaction caused by iron). From all we can learn in the
writings of Pliny and Columella, it appears that the white
alumen must have been a mixture of aluminium sulphate with
more or less sulphate of iron. Why it was called alumen is
not certainly known, but it was probably derived from lumen,
light, in allusion to its brightening the colors when used in
dyeing.
About the eighth century a very pure alumen was made in
Rocca, near Smyrna, and hence called alumen Rocca, or in
modern times, rock alum. This was, indeed, a pure sulphate
of aluminium with sulphate of potash; in fact, our modern
alum, diflfering from the ancient alumen in that it contained
potassium, and was manufactured with care instead of being
merely a natural substance. The old name was, however, still
attached to the new product, and included in its scope the
vitriols, that is, the sulphates of iron and copper. Even in the
thirteenth century alum and vitriol vvere named together as re-
lated substances.
* Book 35, chapter 15.
(O
2 ALUMINIUM.
Paracelsus* in the sixteenth century first separated alum and
vitriols, on the ground that the base of the vitriols was metallic
and that of alum earthy.
Ettmiillerf discovered in 1684 that "alum is obtained by
acting on clay with sulphuric acid."
Stahl in 1702 expressed clearly his conviction that the un-
known base of alum was of the nature of lime or chalk, and for
fifty years thereafter this was the generally accepted idea.
Hoffman $ twenty years later announced that the base of
alum appeared to him to be a true, distinct earth. GeofiTroy,
in 1728, Hellot, in 1739, and Pott, in his famous Lithogeognosia,
in 1746, all reiterated this statement with increasing certainty,
until it was finally generally received as an accepted fact, and
the last named chemist gave it the name of thonichte erde, or
terre argilleuse.
In 1754 Marggraff,§ in three able dissertations on alum and
its earth, showed that this earth is certainly a distinct substance,
that it exists in all natural clays and can be extracted therefrom
by sulphuric acid, that the part of the clay not touched by the
acid is silica, and that, therefore, the purest white clay contains
only silica and the earthy base of alum. These memoirs settled
conclusively the composition of clay, and give rise to the term
argil or argil pier as the name of the earthy base of alum. It
was thus called until 1761, when Morveau,|| intent on revising
chemical nomenclature, decided that since alum was called sel
alumineux, the proper name for its base should be altimine,
thus avoiding all confusion with argille and terre argilleux, the
terms designating clay and clayey earth. In German, however,
the earth of alum is still called thonerde — clay earth ; in English,
the French alumine was adhered to until about 1820, when it
was anglicised into alumina.
* Book 3, p. 64.
t Chymia Rationalis ac Experimentalis.
X Observationem physico-chemicarum Selectiorium, 1722,
§ Opusc. Chim. de Marggraff, I, p. 8.
II Dictionnaire de Physique, Article "Alun."
HISTORY OF ALUMINIUM. 3
Returning to the time of Marggraff, we find soon after the
pubHcation of his paper indications that chemists suspected
this newly-identified earth to be a compound body, and the
search after aluminium had truly begun.
Macquer, * in 1758, wrote, "the earth of alum is white, infus-
ible, and I suspect that it has a relation more or less distant
with the metallic earths."
Baron, f a professor of chemistry in Paris, is our first re-
corded experimenter on the isolation of aluminium. In 1760
he communicated a memoir to the Academy in which he said :
" Marggrafif of Berlin has shown us what the earth of alum is
not, without showing very definitely what it is. I believe the
base of alum to be of a metallic nature, for the following
reasons: i. It has almost no properties in common with the
known earths. 2. It has analogies with the metallic earths, e. g.,
its astringent salts." Baron then proceeds to say that he had
tried all known methods of reducing this base, but without re-
sult, and concludes by saying, " If I had been fortunate enough
to reduce the base of alum to a metal, no other argument would
be needed, and that which to-day I conjecture would be a de-
monstrated fact. I am far from regarding the problem as an
impossibility. I think it not too venturesome to predict that
a day will come when the metallic nature of the base of alum
will be incontestably proven."
Baron does not record the manner in which he tried to re-
duce alumina, but it is probable that he mixed it with carbon
or some organic substance, with salt or soda for flux, and
heated as highly as possible in a charcoal fire. We neverthe-
less have his word that he tried all the methods of reduction
then known.
Lavoisier % regarded it as highly probable that alumina was
the oxide of a metal, the aflSnity of the metal for oxygen being
* Memoires de Paris, 1758.
t Memoires de 1' Acad. Royale, April l6, 1760, p. 274.
t Journal de Physique, May, 1782.
4 ALUMINIUM.
SO strong that neither carbon nor any of the reducing agents
then known was able to overcome it.
Ruprecht and Tondi,* two Austrian chemists, repeated
Baron's experiments in 1790. They thought that hitherto the
reducing agent had not been intimately enough mixed with the
alumina, and that the temperature used had not been sufficiently
high, so they mixed alumina very intimately with charcoal dust,
made it into a paste with oil, and spread it on the inner walls
of a Hessian crucible, which was finally filled up with powdered
charcoal and a layer of bone ash placed on top. Putting the
crucible in a forge, a strong fire was kept up for three hours.
As a result, small metallic particles were found on the inner
sides of the crucible. These they supposed to be the metallic
base of alumina.
Sav4resi,f in Italy, and Klaproth and Karsten, in Germany,
duplicated this experiment with similar results, and then
analyzed the globules of metal obtained. They found them to
be phosphide of iron, the iron coming from the charcoal used
and the phosphorus from the bone ash. Professor Klaproth
referred to this incident as " the pretended metallization of the
earths," and said further, " if there exists an earth which has
been put in conditions where its metallic nature should be dis-
closed, if it had such, an earth exposed to experiments suitable
for reducing it, tested in the hottest fires by all sorts of
methods, on a large as well as on a small scale, that earth is
certainly alumina, yet no one has yet perceived its metalli-
zation."
Lavoisier succeeded in melting alumina in a charcoal fire fed
by pure oxygen. Dr. Hare, in 1802, melted it with the oxy-
hydrogen blow- pipe to a white enamel, but noticed no signs of
reduction to metal.
In 1807 Sir Humphry Davy attacked the alkaline earths
with his great battery which had isolated potassium and so-
* Allgemeiner Zeitung, Nov., 1 790.
t Annales de Chimie, 1791, »., 254.
HISTORY OF ALUMINIUM. 5
dium. His first experiment, mixing alumina with red oxide of
mercury, and passing the electric current through this in con-
tact with metallic mercury, gave no result. He then melted
alumina with potash, and passed the current from 500 plates
through it. The receiving blade received a metallic coating,
and on dipping it into water the latter was decomposed, and
afterwards the solution was proved to contain alumina. An
experiment with soda gave a similar result. Davy had in fact
electrolyzed the aluminates of potassium and sodium, and ob-
tained metallic alkali and aluminium, but he was unable to
isolate the latter by any means he could devise.
Davy next tried to reduce alumina by heating it with metal-
lic potassium. Some potassium oxide was formed, showing
some reduction had taken place, but he could find no metal.
In 1809 Davy had a new battery of 1000 plates, and with it
fused iron to whiteness in the arc in contact with alumina.
The iron became somewhat whiter, and when dissolved in acids
showed that it contained aluminium. The fact was thus estab-
lished that alumina can be decomposed while fiuid in the electric
arc, and its metal alloyed with iron.
Davy next mixed alumina with potassium and iron filings,
hoping that the iron would collect any metal reduced from the
alumina. On melting this mixture a button resulted which
was white and harder than iron, and was undoubtedly an alloy
of iron and aluminium, but Davy could not separate the two
metals. In concluding the recital of his experiments he said,
" Had I been fortunate enough to isolate the metal after which
I sought, I would have given it the name alumium.
In making this suggestion it is perfectly plain that Davy in-
tended this word to represent the metal from alum, simply
starting with alum, and adding ium as the proper termination.
Objections were very soon thereafter made to this proposed
name, not to the termination ium, which was considered abso-
lutely proper, but to the root or stem of the word. It was
maintained by French, German and Swedish writers that the
name of the new metal should be derived from its oxide, and
6 ALUMINIUM.
that the stem of the word should therefore be alumin, and
thence the name aluminium. Davy was influenced by these
criticisms to the extent of changing in 1812 to alumin-um, but
no writers, except a very few English and, in recent years, some
Americans, have used this spelling.
Prof. Benj. Silliman* was in 1813 repeating Hare's experi-
ment of fusing alumina with the oxy-hydrogen blowpipe. The
alumina was supported on charcoal, and he noticed small me-
tallic globules rolling and darting out from under the fused
mass and burning with a bright light. These globules could
have been nothing else than aluminium reduced from fluid
alumitia by charcoal. The metal burnt, however, almost in-
stantly, and no globules could be obtained.
The Swedish chemist Oersted believed, in 1824, that he had
isolated aluminium. He used anhydrous aluminium chloride
as a starting point, and heated it with potassium amalgam,
thinking that the potassium would reduce the chloride and
leave an amalgam of aluminium and mercury, from which the
latter could be distilled away. Potassium, however, when
amalgamated with mercury is not powerful enough to reduce
aluminium chloride, although it can reduce it if used alone, and
so Oersted missed, by a very little, the honor of first isolating
aluminium.
Berzelius was also a worker on the aluminium problem. He
wrote to Sir Humphry Davy, in 1809, that he had reduced
alumina by heating it with carbon in the presence of iron, but
it is probable that he found himself mistaken, as he does not
refer to this matter in any of his later writings ; once, however,
he came within a very little of succeeding. He had studied
the composition and formula of the mineral cryolite, had made
it artificially, and also the corresponding potassium salt. It
then occurred to him that this latter salt might be reduced by
metaUic potassium. He made the experiment in a crucible,
carefully washed the fusion with water, but found no metal. It
* Memoirs Connecticut Acad, of Arts and Science. Vol. I, 1813.
HISTORY OF ALUMINIUM. 7
is quite evident that his sole mistake was in using an excess of
potassium, which, after the reduction, gave on sokition in water
a caustic alkah sokition, which immediately dissolved all the
reduced aluminium. Had he used an excess of the fluoride
salt, the story would almost certainly have read difTerently, be-
cause this reduction has since then been repeatedly performed.
The date of this experiment was 1825.
In 1827, Frederick Wohler, Professor of Chemistry at the
University of Gottingen, after repeating Oersted's experiment
with unsatisfactory results, modified the experiment by using
FREDERICK WOHLER.
pure potassium as the reducing agent, instead of its amalgam.
He obtained a grey, metallic powder, which was finely-divided
aluminium. He was unable to melt this powder into a button,
so as to determine its properties en masse, but he described many
of its chemical properties, and produced from it some alumin-
ium compounds which had not been before made, such as the
sulphide and arsenide. This powder was not absolutely pure
aluminium, as it contained a little platinum from the crucible
in which the reduction was performed, and some potassium,
which lessened its resistance to chemical agents. At that time
8 ALUMINIUM.
no further use was made of these facts. Later, in 1845, on
making vapor of aluminium chloride pass over potassium
placed in platinum boats, Wohler obtained the metal in small
malleable globules of metallic appearance, from which he was
able to determine the principal properties of aluminium. But
the metal thus obtained was scarcely as fusible as cast iron,
without doubt because of the platinum with which it had
alloyed during its preparation. In addition to this, it decom-
posed water at io6°C, from which we suppose that it was still
impregnated with potassium or aluminium chloride. It is to
H. ST. CLAIRE DKVIIXE.
H. St. Claire Deville that the honor belongs of having, in 1854,
isolated aluminium in a state of almost perfect purity, deter-
mining its true properties.
Thus, while aluminium had been isolated in 1827, for
eighteen years its properties en masse were unknown, and it
was only at the end of twenty-seven years after its discovery
that the true properties of the pure metal were established by
Deville. The second birth of aluminium, the time at which it
stepped from the rank of a curiosity into the number of the
useful metals, dates from the labors of Deville in 1854. If
HISTORY OF ALUMINIUM. 9
Wohler was the discoverer of aluminium, Deville was the
founder of the aluminium industry.
In commencing researches on aluminium, Deville, while he
applied the method of Wohler, was ignorant of the latter's results
of 1845. Besides, he was not seeking to produce aluminium
that he might turn its valuable properties to practical account,
but that it might serve for the production of aluminium prot-
oxide (AlO), which he believed could exist as well as ferrous
oxide (FeO). The aluminium he wished to prepare would, he
thought, by its further reaction on aluminium chloride, form
aluminium proto-chloride (AlCP), from which he might derive
the protoxide and other proto-salts. But on passing vapor of
aluminium chloride over the metallic powder formed by reduc-
tion by potassium, this proto-chloride was not thus produced;
he obtained, inclosed in a mass of aluminium-potassium chlo-
ride (AICI3.KCI), fine globules of a brilliant substance, ductile,
malleable, and very light, capable of being melted in a mufifle
without oxidizing, attacked by nitric acid with diflSculty, but
dissolved easily by hydrochloric acid or caustic potash with
evolution of hydrogen.
Deville troubled himself no more about the proto-salts of
aluminium, but, recognizing the importance of his discovery,
turned his attention to preparing the metal. He was at this
time Professor of Chemistry in the Ec^le Normale, Paris ; his
salary was but 3000 francs, his estate was small, and he was
practically without the means of doing anything further.
On Monday, February 6, 1854, Deville read at the .seance of
the Academy a short paper entitled "Aluminium and its Chemi-
cal Combinations," in which he explained the results of this
experiment as showing the true properties of aluminium,
and also furnishing a method of purifying it, and declared his
intention of commencing immediate search for a process which
could be economically applied on a commercial scale. M.
Thenard, at the close of the communication, remarked that such
experiments ought to be actively pursued, and that, since they
were costly, he believed the Academy would hasten the accom-
lO ALUMINIUM.
plishment of the work by placing at Deville's disposal the neces-
sary funds. As the outcome of this, the Academy appointed
Deville one of a committee to experiment on producing alumin-
ium, and 2000 francs were placed at his disposal for the work.
It was on the occasion of the reading of this paper that M.
Chenot addressed a note to the Academy on the preparation
of aluminium and other earthy and alkaline metals, in which he
claimed, in some regards, priority for his inventions. (See
further under "Reduction by Carbon.") This note was re-
served to be examined by a commission appointed to take
notice of all communications relative to the production of
aluminium.
With the funds thus placed at Deville's disposal, he experi-
mented at the Ecole Normale for several months. As potas-
sium is very dangerous to handle, cost then 900 francs a kilo,
and gives comparatively but a small return of aluminium, De-
ville, in view of the successful work of Bunsen on the electric
decomposition of magnesium chloride, tried first the reduction
of aluminium chloride by the battery. On March 20, 1854,
Deville announced to the Academy in a letter to Dumas that
he had produced aluminium without alkaline help, and sent a
leaf of the metal thus obtained. At that time Thenard, Boussin-
gault, Pelouze, Peligot, and later, de-la-Rive, Regnault, and
other well-known scientists, shared the honor of assisting in the
laboratory experiments. Deville sent, in the following May, a
mass of five or six grammes weight to Liebig, making no secret
of the fact that it was reduced by the battery ; while Balard at
the Sorbonne, and Fremy at the Ecole Polytechnique, publicly
repeated his experiments and explained them in all their de-
tails. Although these experiments succeeded quite well, yet
because of the large consumption of zinc in the battery used
the process could evidently not be applied industrially, and
Deville felt obliged to return to the use of the alkaline metals.
Towards the middle of 1854 Deville turned to sodium, with-
out a knowledge of those properties which render it so prefer-
able to potassium, but solely because of its smaller equivalent
HISTORY OF ALUMINIUM. I I
(23 to that of potassium 39) and the greater cheapness of soda
salts. He studied the manufacture of sodium, with the aid of
M. Debray, in his laboratory at the Ecole Normale, and their
experiments were repeated at Rousseau Bros.' chemical works
at Glaciere, when they were so successful that Rousseau Bros,
very soon put metallic sodium on the market at a much reduced
price. It is said that while metallic sodium was a chemical
curiosity in 1855, costing something like 2000 francs a kilo, its
cost in 1859 is put down at 10 francs. Deville carried this pro-
cess to such perfection that for twenty-five years it remained
almost precisely at the status in which he left it in 1859. In
order to still further cheapen aluminium, Deville busied himself
with the economic production of alumina, which gave later a
lively impulse to the cryolite and bauxite industries.
On August 14, 1854, Deville read a paper before the Acad-
emy describing his electrolytic methods at length (see under
"Reduction by Electricity"), showing several small bars of the
metal, and also stating some of the results already achieved by
the use of sodium, but not going into details, since he believed
that numerous analyses were necessary to confirm these results
— which he was unable to have made with the funds at his dis-
posal. He also stated that the desire to show, in connection
with his assertions, interesting masses of the metal, alone pre-
vented the earlier publication of the methods used. Several
days before this, Bunsen published in Poggendorif's Annalen
a process for obtaining aluminium by the battery, which re-
sembled Deville's method, but of which the latter was ignorant
when he read his paper. Thus it is evident that the isolation
of aluminium by electrolysis was the simultaneous invention of
Deville and Bunsen.
After reading this paper, Deville caused a medal of alumin-
ium to be struck, which he presented to the Emperor Na-
poleon III. The latter, looking forward to applying such a
light metal to the armor and hemlets of the French Cuirassiers,
immediately authorized experiments to be continued at his own
expense on a large scale. This anticipation ultimately proved
12 ALUMINIUM.
impracticable, but the ambition in which it was bred was caused
for once to minister to the lasting benefit of mankind. Deville,
however, about this time accepted, in addition to his duties as
professor at the Ecole Normale, a lectureship at the Sorbonne
(where he afterwards obtained a full professorship), and it was
not until March of the next year that the experiments at the
cost of the Emperor were begun.
It was about August, 1854, that two young chemists, Chas.
and Alex. Tissier, at the suggestion of Deville, persuaded M.
de Sussex, director of a chemical works at Javel, to let them
experiment in his laboratory (of which they had charge) on
the production of sodium.
Towards the commencement of 1855, Deville took up the in-
dustrial question, the Emperor putting at his disposition all the
funds necessary for the enterprise, and in March the investigator
went to work and installed himself at the chemical works at
Javel in a large shed which the director, M. de Sussex, kindly
put at his service.
The investigations were carried on here for nearly four
months, ending June 29th, and the process elaborated was an
application on a large scale of the experiments he had made at
the expense of the Academy, which he described in his paper
of August 14, 1854, and by which he had been able to obtain
a few pencils of metal. In this work such success attended his
efforts that on June 18 Deville presented to the Academy
through M. Dumas large bars of pure aluminium, sodium, and
masses of aluminium chloride. The members and large audi-
ence were loud in their admiration and surprise at the beauty
of the metal. Dumas stated that the experiments at Javel had
put beyond a doubt the possibility of extracting aluminium on
a large scale by practical processes. Deville's paper was then
read, describing all his processes in detail, and concluding with
the following words : " After four months of work on a large
scale, undertaken without responsibility on my part, and, in
consequence with the tranquility and repose of mind which are
so often wanting to the investigator, without the preoccupation
HISTORY OF ALUMINIUM. 1 3
of expense, borne by His Majesty the Emperor, whose gen-
erosity had left me entire liberty of action, encouraged each
day by distinguished men of science, I hope to have placed the
aluminium industry on a firm basis."
It was the metal made at this time at Javel which was ex-
hibited at the Paris Exposition in 1855. In the Palais de I'ln-
dustrie, among the display from the porcelain works at Sevres,
were ingots and some manufactured objects. The first article
made of aluminium was, in compliment to the Emperor, a baby-
rattle for the infant Prince Imperial, for which purpose it must
have served well, because of the sonorousness of the metal.
After terminating these experiments Deville continued work-
ing at the Ec61e Normale, the Emperor defraying his expenses,
until April, 1856. The memoir published in the Ann. de Chim.
et de Phys., April, 1856, contains, besides the results obtained
at Javel, the improvements devised in the meantime.
It appears that when Deville first went to Javel, he had for
assistants the Tissier Brothers, who were charged by M. de
Sussex to give him all the aid they could. Since the previous
autumn the Tissiers had been experimenting on sodium fur-
naces, and now, in concert with Deville, they drew up plans for
furnaces, and aided in devising other apparatus. Under these
circumstances the furnace for the continuous manufacture of
sodium in cylinders was devised, which the Tissiers claim De-
ville strongly advised them to make their property by patenting,
asking only from them the use of it for his experiments. So,
immediately after the experiments were ended, in July, the
Tissiers patented the furnace in question, and, leaving Paris,
took charge of M. Chanu's works at Rouen. On the other
hand, Deville always reproached them for acting in bad faith.
He says that after having assisted for about two months in set-
ting up his apparatus, being forced to leave the works because
of misunderstandings between them and M. de Sussex, they
were admitted to his laboratory at the Ecole Normale, and
initiated by him into the knowledge of all those processes
which they made use of afterwards, then suddenly left, taking
14 ALUMINIUM.
drawings of furnaces, details of processes, etc., which they not
only made free use of, but even patented. However, whichever
party was in the right (and those who comprehend the char-
acter of Deville can hardly doubt which was), the fact stands
that in July, 1855, M. Chanu, an honorable manufacturer of
Rouen, founded a works in which Deville's processes were to
be applied, and intrusted the direction of it to the Tissier
Brothers.
The history of the works at Rouen is thus described by the
Tissiers in their book on aluminium, of which we shall speak a
little further on :
"la July, 185s, Messrs. Maletra, Chanu, and Davey, of
Rouen, formed a company to produce aluminium, and we were
intrusted with the organization and special charge of the in-
dustry. The commencement was beset with difficulties, not
only in producing, but in using the metal. It then sold at $200
per kilo, the price being an insurmountable obstacle to its em-
ployment in the arts. The small capital at our disposal was
not enough to start the industry, to pay general expenses, and
the losses occasioned by the many experiments necessary. On
February 28, 1856, the society was dissolved. In April of the
same year, M. William Martin, struck by the results already
obtained and sanguine of greater success, united with us. From
that time daily improvements confirmed M. Martin's hopes,
and in 1857 the works at Amfreville-la-mi-Voie, near Rouen,
sold the metal at $60 per kilo ($2 per oz.). The laboratory
of this works was devoted to researches on everything concern-
ing the production and application of aluminium. M. Martin
has our sincere gratitude for the kindness with which he so
willingly encouraged and contributed to the progress of the
manufacture of this wonderful metal."
The process ultimately used at Amfreville was the reduction
of cryolite by sodium, but the enterprise was not a permanent
success, and after running for a few years it was abandoned and
the works closed.
Returning to Deville, we find that after leaving Javel one of
HISTORY OF ALUMINIUM. I 5
the first subjects he investigated was the use of cryolite for
producing aluminium. The researches made with the aid of
MM. Morin and Debray were published in the memoir of April,
1856, and became the basis of the process carried out by the
Tissiers at Rouen. Besides this, Deville perfected many of the
details of a practical aluminium plant, with the result that in
the spring of 1856 he united with Messrs. Debray, Morin, and
Rousseau Bros, (the latter manufacturers of chemicals at Gla-
ciere, in whose works aluminium had been made since the
middle of 1855) and put up new apparatus in the works at
Glaciere, the company furthering the work entirely at their own
cost. This enterprise lasted for more than a year, during which
a number of processes were tried and continued improvements
made, so that towards August of the same year aluminium
was put on the market in Paris at 300 francs a kilo, being one-
third what it cost a year previous.
Finally, in April, 1857, the little works at Glaciere, a suburb
of Paris, in the midst of gardens and houses, and turning into
the air fumes charged with chlorine and salts, was obliged by
reason of general complaints to stop making aluminium. The
plant was moved to Nanterre, where it remained for some years,
under the direction of M. Paul Morin, being on a scale four
times as large as the actual demand. Afterwards part of the
plant was moved to the works of H. Merle & Co., at Salindres,
and later on the whole plant, where the manufacture was until
recently carried on by Pechiney & Co. The works at Nan-
terre were really the only "aluminium works" built by Deville,
the others were plants installed at general chemical works ; but
these at Nanterre were built by the united efforts of Deville,
his brothers and parents, and a few personal friends. Among
those who aided Deville, especially in the problems which the
new industry presented, he speaks warmly of Messrs. d'Eichtal,
Lechatelier, and Jacquemont.
In 1858 the Tissiers wrote and published- a small work
entitled " Recherches sur 1' Aluminium." which, in view of what
Deville could have written about the subject, was a decided
l6 ALUMINIUM.
misrepresentation of the results which had been thus far accom-
plished. Deville thought that the industry was yet too young
to merit any sort of publication, yet he naively writes in his
work "De 1' Aluminium," in 1859, "I will sincerely acknowl-
edge that my writing is a little due to my pride, for I decided
to take the pen to speak of my work, only to avoid seeing it
belittled and disfigured as it has been lately in the book written
by MM. Tissier."
Deville published his book in September, 1859, and he con-
cludes it with these words : " I have tried to show that alumin-
ium may become a useful metal by studying with care its
physical and chemical properties, and showing the actual state
of its manufacture. As to the place which it may occupy in
our daily life, that will depend on the public's estimation of it
and its commercial price. The introduction of a new metal
into the usages of man's life is an operation of extreme diffi-
culty. At first aluminium was spoken of too highly in some
publications, which made it out to be a precious metal, but
later these estimates have depreciated even to the point of con-
sidering it attackable by pure water. The cause of this is the
desire which many have to see taken out of common field-mud
a metal superior to silver itself ; the opposite opinion established
itself because of very impure specimens of the metal which were
put in circulation. It seems now that the intermediate opinion,
that which I have always held and which I express in the first
lines of my book, is becoming more public, and will stop the
illusions and exaggerated beliefs which can only be prejudicial
to the adoption of aluminium as a useful metal. Moreover,
the industry, established as it now is, can be the cause of loss
to no one ; as for myself, I take no account of the large part of
my estate which I have devoted, but am only too happy if my
efforts are crowned with definite success, in having made fruit-
ful the works of a man whom I am pleased to call my friend,
the illustrious Wohler."
Contemporary with the early labors of Deville, among the
numerous chemists and metallurgists investigating this attract-
HISTORY OF ALUMINIUM. 1 7
ive field, we find Dr. Percy in England and H. Rose in Ger-
many, whose experiments on the reduction of cryolite by
sodium were quite successful, and are herein described later on.
As early as 1856 we find an article in an American magazine *
showing that there were already chemists in the United States
spending time and money on this subject. The following is the
substance of the article alluded to: "Within the last two years
Deville has extracted 50 to 60 lbs. of aluminium. At the pres-
ent time, M. Rousseau, the successor of Deville in this manu-
facture, produces aluminium which he sells at $100 per pound.
No one in the United States has undertaken to make the metal
until recently Mons. Alfred Monnier, of Camden, N. J., has,
according to the statement of Prof. James C. Booth in the
" Penn. Inquirer," been suceessful in making sodium by a con-
tinuous process, so as to procure it in large bars, and has made
aluminium in considerable quantity, specimens of which he has
exhibited to the Franklin Institute. Mons. Monnier is desirous
of forming a company for the manufacture of aluminium, and is
confident that by operating in a large way he can produce it at
a much less cost than has heretofore been realized. We would
suggest the propriety of giving aid to this manufacture at the
expense of the government, for the introduction of a new metal
into the arts is a matter of national importance, and no one can
yet realize the various and innumerable uses to which this new
metal may be applied. It would be quite proper and constitu-
tional for Congress to appropriate a sum of money, to be ex-
pended under the direction of the Secretary of the Treasury in
the improvement of this branch of metallurgy, and in testing
the value of the metal for coinage and other public use."
In the next volume of the "Mining Magazine"! there is a
long article by Mr. W. J. Taylor, containing nothing new in
regard to the metallurgy of aluminium, but chiefly concerned
in calculating theoretically the cost of the metal from the raw
* Mining Magazine,. 1856, vii., 317.
t Mining Magazine, viii., 167 and 228. Proc. Ac. Nat. Sci., Jan., 1857.
2
1 8 ALUMINIUM.
materials and labor required by Deville's processes, and con-
cluding that it was quite possible to make it for $ i .00 per pound.
In 1859 the first aluminium works in England were started at
Battersea, near London, by C. H. Gerhart, using Deville's pro-
cess. No details are obtainable respecting the size of this
works. M. Henri Brivet informs me that they had no connec-
tion with Bell Bros.' enterprise, started the next year after, and
that they closed operations about 1865.
In i860, Bell Bros, established a plant at Washington, near
Newcastle-on-Tyne, with the immediate co-operation of Deville.'
In 1862 this company was selling aluminium at 40 shiUings per
troy pound, and they continued operations until 1874, when
they closed because the business was no longer profitable.*
It was probably shortly after 1 874 that the large firm of J. F.
Wirtz & Co., Berlin, made an attempt to start an aluminium
works. The project drooped before it was well started ; and it
is only within the last few years that Germany has possessed a
flourishing aluminium industry.
The further we get away from an age the better able are we
to write the true history of that age. And so as years pass
since the labors of Wohler, Deville, and Tissier, we are now
able to see better the whole connected history of the develop-
ment of this art. Dr. Clemens Winckler gives us a compre-
hensive retrospect of the field seen from the standpoint of 1879,
from which we condense the following : -j- " The history of the
art of working in aluminium is a very short one, so short that
the present generation with which it is contemporary is in dan-
ger of overlooking it altogether. The three international exhi-
bitions which have been held in Paris since aluminium first
began to be made on a commercial scale form so many memo-
rials of its career, giving as they did at almost equal intervals
evidence of the progress made in its application. In 1855 we
meet for the first time in the Palais de 1' Industrie with a large
* Personal communication to the writer from Sir Lowthian Bell,
t Industrie Blatter, 1879; Sci. Am. Suppl., Sept. 6, 1879.
HISTORY OF ALUMINIUM. 1 9
bar of the wonderful metal, docketed with the extravagant
name of the ' silver from clay.' In 1 867 we meet with it again
worked up in various forms, and get a view of the many diffi-
culties which had to be overcome in producing it on a large
scale, purifying and moulding it. We find it present as sheets,
wire, foil, or worked-up goods, polished, engraved, and soldered,
and see for the first time its most important alloy, aluminium
bronze. After a lapse of almost another dozen years we see at
the Paris Exhibition of 1878 the maturity of the industry. We
have passed out of the epoch in which the metal was worked
up in single specimens, showing only the future capabilities of
the metal, and we see it accepted as a current manufacture
having a regular supply and demand, and being in some re-
gards commercially complete. The despair which has been
indulged in as to the future of the metal is thus seen to have
been premature. The manufacture of aluminium and goods
made of it has certainly not taken the extension at first hoped
for in its behalf ; the lowest limit of the cost of manufacture was
soon reached, and aluminium remains as a metal won by ex-
pensive operations from the cheapest of raw materials.
" There are several reasons why the metal is shown so little
favor by mathematical instrument makers and others. First of
all, there is the price ; then the methods of working it are not
everywhere known ; and further, no one knows how to cast it.
Molten aluminium attacks the common earthen crucible, re-
duces silicon from it, and becomes gray and brittle. This
inconvenience is overcome by using lime crucibles, or by lining
an earthen crucible with carbon or strongly burnt cryoHte clay.
If any one would take up the casting of aluminium and bring it
into vogue as a current industrial operation, there is no doubt
that the metal would be more freely used in the finer branches
of practical mechanics."
At the time of Dr. Winckler's writing, the extraction of
aluminium in France was carried on by Merle & Co., at Salin-
dres, while the Societe Anonyme de 1' Aluminium, at Nanterre,
worked up the metal. Both firms were represented at the Ex-
20 ALUMINIUM.
position of 1878. The prices quoted then were 130 francs a
kilo for aluminium, and 18 francs for 10 per cent, aluminium
bronze. From 1874, when Bell Bros.' works at Newcastle-on-
Tyne stopped operations, until 1882, when a new enterprise
was started in England by Mr. Webster, the French company
were the only producers of aluminium.
Regarding the prospects of the aluminium industry at this
period, we can very appropriately quote some remarks of the
late Mr. Walter Weldon, F. R. S., who was a personal friend of
M. Pechiney (director of the works at Salindres), had given
great attention to aluminium, and was considered as a first
authority on the subject. Speaking in March, 1883, before the
London Section of the Society of Chemical Industry, he stated
that the only method then practiced for the manufacture of
aluminium was DeviUe's classical one; that at Salindres, M.
Pechiney had improved and cheapened it, but that was all the
progress made in the industry in twenty-five years. Continu-
ing, Mr. Weldon outlined the possible lines on which improve-
ments might be made, as :
1st. Cheapening the production of aluminium chloride, or of
aluminium-sodium chloride.
2d. Substituting for these chlorides some other cheaper
anhydrous compounds of aluminium not containing
oxygen.
3d. Cheapening sodium.
4th. Replacing sodium by a cheaper reducing agent.
Mr. Weldon exhibited the relative cost of the materials used
in making aluminium, as then carried on by M. Pechiney, as :
Producing the alumina 10 per cent.
" " double chloride 33 "
" " sodium and reducing therewith 57 "
"Discussing these figures, it is seen that the cost of the alu-
mina forms but a small item in the cost of the metal, since a
saving of 50 per cent, in its cost would only cheapen the metal
5 per cent. A large margin is, however, left in the conversion
HISTORY OF ALUMINIUM. 2 1
of the alumina into the chloride, and it is here that a large sav-
ing may be expected, either in cheaper methods of producing
the chloride or by the substitution of some other cheaper salt
for the chloride. The only other suitable compounds which
might replace the latter are the fluoride, iodide, bromide, sul-
phide, phosphide, or cyanide. The fluoride has been used to
some extent in the form of cryolite, but, from the impurities in
the mineral and its corrosive action on the apparatus used for
reduction, the metal produced is very much contaminated with
iron and silicon. The bromide and iodide, no matter how pro-
duced, would always be too costly to replace the chloride. The
production of the sulphide in a suitable form from which the
metal can be extracted has thus far not proved a success, and
even if ever it be thus produced in a suitable condition, it is not
at all likely to be as cheap a material to use as the chloride.
The phosphide and cyanide can thus far only be produced from
the metal itself, and are, therefore, totally out of the question.
To find a substitute for sodium as a reducing agent has been a
favorite object of research among chemists for the past thirty
years, and although every element occurring in any abundance,
or obtainable at a cheaper rate than sodium, has been tried
under almost all conditions, yet absolutely nothing has been
accomplished in this direction that would entitle any one to the
belief that aluminium can ever be produced chemically without
the use of sodium. So absorbing to those interested in the
search for a substitute for sodium has the occupation proved,
that the effort to cheapen sodium did not receive anything like
its fair share of attention. Since of the 57 per cent, ascribed
to the cost of sodium and reduction, 50 per cent, represents the
sodium, which thus costs about six shillings a pound, there is
seen to be a very large margin for improvements, since the raw
materials for a pound of sodium do not cost over i or at most
2 shillings."
In 1882 the cost of aluminium was materially cheapened by
the applications of the inventions of Mr. Webster, which, in ac-
cordance with the analysis of the problem made by Mr. Weldon,
2 2 ALUMINIUM.
consisted principally in the cheap production of alumina and its
conversion into chloride. Mr. Webster had experimented on
this subject many years, and in 1881 and 1882 took out patents
for his processes, and organized the "Aluminium Crown Metal
Company," located at Hollywood, near Birmingham, where
several thousand pounds were expended in plant. Business
was soon commenced on a large scale, the company produc-
ing, however, many other alloys besides those of aluminium.
The business grew until it soon became the serious competitor
of the French company, and practically controlled the English
market. However, a radical change of still greater importance
in the sodium process was made in 1886 by an invention of
Mr. H. Y. Castner, of New York City. This gentleman con-
ceived the plan of reducing sodium compounds in cast-iron
pots, from a fused bath of caustic soda, by which the reduction
is performed at a much lower temperature, and the yield of
sodium is very much more than by the Deville method. The
application of this process on a large scale, with the use of gas
furnaces and other modern improvements, has lowered the cost
of sodium from $1 per pound to about 20 or 25 cents. It is
but just to say that Mr. Castner's invention was by no means a
chance discovery. For four years he worked in a large labor-
atory fitted up for this special purpose, and after many dis-
couragements in trying to produce aluminium by means other
than that of sodium, was led finally to consider that the cheap-
ening of this metal was the most promising method for cheap-
ening aluminium, and after much patient, hard work, success
was at last reached.
Mr. Castner's patent was taken out in the United States in
June, 1 886, and, while being the first one granted on that sub-
ject in this country, is said also to be the only one taken out in
the world since 1808. With the assistance of Messrs. J. H. and
Henry Booth, of New York City, Mr. Castner demonstrated the
process by building and operating a furnace on a somewhat
large scale. This being accomplished, Mr. Castner crossed to
England and met the representatives of the Webster process.
HISTORY OF ALUMINIUM. 23
with whom it was evident a combination would be especially
advantageous to both parties ; for, with cheap aluminium chlor-
ide and cheap sodium, it was clear that a strong process could
be built up. Mr. Castner then demonstrated plainly, by erect-
ing a furnace and operating it for several weeks, that his pro-
cess was all that he claimed for it. As a result of this success,
the "Aluminium Company, Limited," was incorporated in June,
1887, with a share capital of .£'400,000, " to acquire the patents
and work and develop the inventions of James Webster for the
manufacture of pure alumina and certain metallic alloys and
compounds, together with the business at present carried on by
the Webster Patent Aluminium Crown Metal Company, Lim-
ited, in Birminghami, Sheffield, and London, England, and also
to acquire the patents and work and develop the invention of
H. Y. Castner for the manufacture of sodium and potassium."
Mr. Webster was paid ;£'2 30,000 for the business, properties,
stock, etc., of the Crown Metal Company, while ;£'i40,ooo was
allowed for the sodium patents. The new company appointed
Mr. Castner managing director, and the erection of large works
was immediately begun at Oldbury, near Birmingham. These
works were started in operation at the end of July, 1888. They
covered five acres of ground, and their daily production for
some time was about 250 pounds, which was sold at 20 s. per
pound. This was increased during 1889 to nearly 500 pounds
a day, and the selling price of the aluminium decreased to 16
shillings. Early in 1891, however, this company was forced to
stop the manufacture of aluminium, as its selling price was re-
duced by the owners of the electrolytic processes below 4 shil-
lings per pound, at which price the sodium processes could no
longer compete. The company continued in the sodium busi-
ness, and in 1893, with their original capital of .£400,000 writ-
ten down to ;£^8o,ooo, we hear that they are doing a prosperous
business under Mr. Castner's direction, producing sodium and
sodium peroxide, and making caustic soda and bleaching
powder by electrolysis of common salt. In view of the promi-
nent part which this works took in the aluminium industry from
24 ALUMINIUM.
1888 to 1 89 1, and as an acknowledgment to Mr. Castner's able
direction, the methods there used have been rightly designated
as " The Deville-Castner Process."
We have followed the progress of the Webster and Castner
processes up to the date of starting the works at Oldbury, be-
cause the continuity of the advances made in the old Deville
process would hardly allow of a break in order to mention
other processes arising meanwhile. However, the years since
1884 have witnessed not one but several revolutions in the alu-
minium industry. The great advances made in dynamo-electric
machinery in the last decade have led to the revival of the old
methods of electrolysis descovered by Deville and Bunsen, and
to the invention of new methods of decomposing aluminium
compounds electrolytically. It will be recalled that the first
small pencils of aluminium made by Deville were obtained by
electrolysis, and that he turned back to the use of the alkaline
metals solely because the use of the battery to effect the de-
composition was far too costly to be followed industrially.
This fact still holds true, and we cannot help supposing that if
Deville had had dynamos at his command such as we have at
present, the time of his death might have seen the aluminium
industry far ahead of where it now is.
First in point of time we notice Gratzel's process, patented in
Germany in 1883 and used industrially by the "Aluminium and
Magnesium Fabrik, Patent Gratzel," at Hemelingen, near Bre-
men. The process was essentially the electrolysis of a bath of a
fused aluminium salt, such as chloride or fluoride, the improve-
ments on the older experiments being in details of apparatus
used, the use especially of anodes of mixed carbon and alu-
mina, and the use of dynamic electricity. Several metallurgists
maintained the uselessness of the Gratzel processes, and their
position was proved to be not far from the truth, for in October,
1887, the company announced that the addition " Pt. Gratzel"
would be dropped from the firm name, since they had aban-
doned Gratzel's processes and were making aluminium by
methods devised by Herr Saarburger, director of their works.
HISTORY OF ALUMINIUM. 25
The processes of this latter gentleman not being published, we
are unable to state their nature, but they were very probably
electrolytic. In October, 1888, Mr. Saarburger reported that
their works were producing at the rate of 12,000 kilos of alu-
minium yearly, besides a large quantity of aluminium bronze
and ferro-aluminium. The firm also worked up the aluminium
and its alloys into sheet, wire, tube, etc.
Since 1890, however, this company has retired from the alu-
minium business, their works being now used only for the pro-
duction of magnesium.
A somewhat similar electrolytic process was patented by Dr.
Ed. Kleiner, of Zurich, in 1886. Molten cryolite was decom-
posed by two carbon poles, the heat generated by the current
first melting the cryolite and then electrolyzing it. Since the
motive power in this, as in all electric processes, composes one
of the chief elements for carrying on the reduction, the Kleiner
Gesellschaft, formed to work this method, made an attempt to
obtain water rights at the falls of the Rhine, at Schaffhauseni
which would furnish 15,000 horse-power. This proposition
being refused by the government, an experimental plant was
started at the Hope Mills, Tyddesley, Lancashire, England.
The results were not encouraging enough to allow of commer-
cial success, and the process was abandoned.
An electrolytic method, different in principle from both the
preceding, is the invention of Mr. Chas. M. Hall, of Oberlin,
Ohio, which was patented in the United States in April, 1889,
but applied for in 1886. The principle involved is the electric
decomposition of alumina, dissolved in a fused bath of the
fluorides of aluminium and other bases, the current reducing
the dissolved alumina without affecting the solvent. This
method is essentially different from any of the previous elec-
trical processes, which contemplated and operated simply the
decomposition of a molten aluminium salt, such, for instance, as
the solvent used by Mr. Hall. The knowledge that the fused
fluorides dissolve large quantities of alumina, and that the elec-
tric current will act on this dissolved alumina without decom-
26 ALUMINIUM.
posing the solvent, was the essence of Hall's invention, and the
source of another revolution in the aluminium industry. The
process has been operated by the Pittsburgh Reduction Com-
pany, from 1889 to 1891, in Pittsburgh, Pa., since 1891 at New
Kensington, Pa., on the banks of the Allegheny river, eighteen
miles above Pittsburgh. During 1889 this company produced
about 75 pounds of aluminium a day, which they sold at $4.50
per pound ; in 1 890 their capacity was increased to 400 poun'ds
per day, and the selling price reduced to $2.00 per pound;
since 1892 the works ha,ve been again enlarged to a capacity of
nearly one ton per day, and the selling price has tended stead-
ily downwards until it is at present $0.50 per pound. During
189s this company expects to put into operation a very large
new plant at Niagara Falls, using power generated by the new
tunnel. This works will utilize up to 6,000 horse-power, and
will have a capacity when in full operation of 6,000 to 8,000
pounds per day. This improvement will place the United
States in the front as the largest aluminium-producing country
in the world.
In France, Adolphe Minet, a well-known electrician, experi-
mented during 1887 and 1888 on the electrolysis of a molten
bath containing aluminium fluoride and sodium chloride, fed
by the addition of alumina and aluminium fluoride. From
1888 to 1 89 1 this process was run on an experimental scale
at the works of Bernard Bros., at Creil, making about 35 pounds *
of aluminium per day. In 1890 a larger plant was put up, run
by water power, at Saint Michel, Savoy, having a much larger
capacity, which it is stated had been increased in 1894 to
1,000 pounds per day. In 1895, this plant has been acquired
by a French company who will operate by the Hall process.
While the electrolytic processes so far considered use a fluid
bath, and operate at moderate temperatures with a current of
moderate intensity, there have been devised two other promi-
nent processes which operate in a somewhat different manner
and attain to economical results. These primarily depend on
the enormous temperature attainable by the use of a powerful
HISTORY OF ALUMINIUM. 2/
electric arc, and secondarily on the reduction of alumina (which
at the temperature attained becomes fluid) either by the reduc-
ing action of the carbon present or by simple electric decompo-
sition. Which of these two agencies performs the reduction, in
either process, is still an unsettled question, which we will dis-
cuss later on.
Before going further with the history of these two processes,
Cowles' and Heroult's, it may not be inappropriate to take note
of a few facts antecedent to their appearance. It is well known
that Sir W. Siemens devised an electric furnace in which the
heat of the arc was utilized for melting steel. In 1882 Mr.
Ludwig Grabau, in Hanover, Germany, purchased a Siemens
furnace for the express purpose of attempting the reduction of
alumina, and after experimenting successfully for some time,
modified the apparatus so as to work it continuously, and there-
with made aluminium alloys ; but on account of the difficulties
of the process, and the impurity of the alloys produced, Mr.
Grabau gave up the experiments, having come to the conclu-
sion that aluminium alloys to be technically valuable should be
obtained in a state of almost chemical purity. In the beginning
of 1885 Dr. Mierzinski, in his book on aluminium, presented
some very striking remarks on the use of the electric furnace,
which are so much to the point that they are well worth quoting
in this connection : " The application of electricity for produc-
ing metals possesses the advantage not to be ignored that a de-
gree of heat may be attained with it such as cannot be reached
by a blowpipe or regenerative gas-furnace. The highest furnace
temperature attainable is 2500 to 2800° C., but long before this
point is reached the combustion becomes so languid that the
loss of head by radiation almost equals the production of heat
by combustion, and hinders a further elevation of temperature.
But in applying electricity the degree of heat attainable is theo-
retically unlimited. A further advantage is that the smelting
takes place in a perfectly neutral atmosphere, the whole opera-
tion going on without much preparation, and under the eyes of
the operator. Finally, in ordinary furnaces, the refractory
28 ALUMINIUM.
material of the vessel must stand a higher heat than the sub-
stance in it, whereas by smelting in an electric furnace the
material to be fused has a higher temperature than the crucible
itself. Since the attempt to produce aluminium by the direct
reduction of alumina by carbon is considered by metallurgists
as impossible, because the temperature requisite is not attain-
able, the use of the electric current for attaining this end seems
to be of so much the more importance."
The Cowles invention was patented August i8, 1885, and
was first publicly described before the American Association
for the Advancement of Science, at their Ann Arbor meeting,
August 28, 1885. The process is due to two Cleveland gen-
tlemen, E. H. and A. H. Cowles, who in the development of
their process associated with them Prof. Charles F. Mabery, of
the Case School of Applied Science, Cleveland, as consulting
chemist. The Cowles Electric Smelting and Aluminium Com-
pany, formed to work the process, erected a plant at Lockport,
N. Y., where a water power of 1200 horse-power was secured,
and where, among other novel apparatus, the largest dynamo
in the world, made especially for this purpose by the Brush
Electric Company, was in operation. Following the success of
this plant in America, the Cowles Syndicate Company, organ-
ized to work the patents in England, put in operation works at
Stoke-on-Trent which had a capacity of something like 300
lbs. of alloyed aluminium daily. Springing also from the
Cowles process is the "Aluminium Brass and Bronze Com-
pany," of Bridgeport, Conn., which was organized in July,
1887, and controls the exclusive rights under the Cowles
American patents of manufacturing the alloys of aluminium
into sheet, rods, and wire. The extensive plant of this com-
pany employs 300 men, and has been erected at a cost of nearly
$300,000.
The principle made use of in the Cowles process is, briefly,
that a powerful electric current is interrupted, the terminals
being large carbon rods, and the space between having been
filled with a mixture of alumina, carbon, and the metal to be
HISTORY OF ALUMINIUM. 29
alloyed, the intense heat generated in contact with this mixture
causes the metal to melt and the alumina to be reduced to alu-
minium, which combines with the metal, while the oxygen
escapes as carbonic oxide.
It is interesting to note as separating the Cowles, as well as
the Heroult, process from the previously-mentioned electrolytic
methods, that while the latter produce almost exclusively pure
aluminium in their electric operation, finding it inexpedient, if
not perhaps impossible, to add other metals and form alloys at
once — the former experience almost the reverse of these condi-
tions, and as yet are confined exclusively to the direct produc-
tion of the alloys.
The Heroult process was first put in practical operation on
July 30th, 1888, at the works of the Swiss Metallurgic Com-
pany (Societe Metallurgique Suisse), at Neuhausen, near
Schaffhausen. The patents for the process were granted in
France and England in April and May, 1887, and in the United
States in August, 1888. The company named above is com-
posed of some of the largest metal-workers in Switzerland.
Previously to their adoption of this process they had experi-
mented with Dr. Kleiner's electrolytic method, but abandoned
it, and on becoming the owners of the Heroult process imme
diately started it up practically on a large scale, and with signal
success.
The process consists in electrolyzing molten alumina which
has been rendered fluid by the heat of the arc, using as the
positive anode a large prism of hard carbon and as the negative
a substratum of molten copper or iron, the arrangement of the
parts being such that the process seems to proceed, when once
well under way, in all respects as tlfe simple electrolysis of a
liquid. Using water power for driving the dynamos, the
economical production of alloyed aluminium at 4.5 francs per
kilo (50 cents per pound), was an assured fact.
The success of this process at Neuhausen was so marked as
to attract general attention, and in the latter months of 1 888
several large German corporations, prominent among which was
30 ALUMINIUM.
the Allgemeine Electricitats Gesellschaft of Berlin, sent repre-
sentatives to arrange for the purchase of the Heroult patents
for Germany. The outcome of these examinations and negotia-
tions was the purchase by this German Syndicate of HerouU's
continental patents and the founding by them and the former
Swiss owners of the Aluminium Industrie Actien-Gesellschaft,
with a capital of 10,000,000 francs. In December, 1888, the
new company took possession at Neuhausen, and commenced
the construction of a plant many times larger than the original
one, their plans also including the erection of foundries and
mills for casting and manufacturing their alloys. Dr. Kiliani,
the well-known writer on electro-metallurgical subjects, was
working manager for the company.* The new plant utilized
3000 horse power, and had a capacity of 3000 pounds of alloyed
aluminium daily.
In the same year, the Societe Electro-Metallurgique Fran-
caise established a works at Froges (Isere) 12 miles from
Grenoble, to work the Heroult process, with Kiliani's modifica-
tions. They used 400 horse-power, which later was enlarged
to 800, and in 1894 acquired a large water power at La Praz,
near Modane, where works have been erected and lately put
into operation.
The process now used here and in Switzerland is not the
original Heroult process as previously described. Dr. Kiliani
introduced some modifications in the apparatus, but no pure '
aluminum was made by either of the Heroult works until the
end of 1889, when there was begun the use of cryolite in the
furnace to reduce the melting point of the alumina and the
electrical tension required to operate it. As thus modified, the
process is essentially identical in principle with Hall's process ;
in fact, the U. S. Patent office refused Heroult's application for
a patent on account of Hall's priority to the process. An at-
tempt was made in 1889 to work the Heroult alloy process in
the United States, an experimental plant being started at
* Dr. Kiliani died suddenly in January, 1895, in the midst of his duties.
HISTORY OF ALUMINIUM. 3 1
Bridgeport, Conn., in August of that year, but it was stopped
by the burning out of the dynamo. In 1890 another dynamo
arrived from the Oerlikon works, at Zurich, and the process
was operated for some time on an experimental scale at Boon-
ton, N. J., but was abandoned in 1891.
During the years 1885 to 1890 both the Cowles and Heroult
alloy processes were successful in producing aluminium in al-
loys at a lower cost than the market price of pure aluminium,
and therefore built up a considerable business. Since pure
aluminium has reached so low a price, metal mixers prefer to
make their own alloys from the pure metal, and the ready-made
alloys have lost their market.
The Alliance Aluminium Company of London, England, was
organized in the early part of 1888, with a nominal capital of
^500,000. This company owned the English, German, French,
and Belgian patents of Prof. Netto, of Dresden, for the manu-
facture of sodium and potassium and the reduction of cryolite
thereby ; the patents of Mr. Cunningham for methods of reduc-
tion of the same metals ; and methods devised by Prof. Netto
and Dr. Saloman, of Essen, for producing aluminium of great
purity on a commercial scale. The two latter named gentle-
men are said to have invented their processes after long ex-
perimenting at Krupp's works at Essen; and, since the ap-
paratus used was mounted on trunnions, many rumors were
spread by the newspapers that aluminum was being made (by
tons, of course) in a Bessemer converter by Krupp, of Essen.
Prof. Netto reduced sodium by a continuous process, by allow-
ing fused caustic soda to trickle over incandescent charcoal in a
vertical retort, the apparatus containing many ingenious details
and giving promise of being quite economical. One method of
using the sodium in reduction consisted in the use of a plunger
to which bars of sodium were attached and held at the bottom
of a crucible full of molten cryolite ; another depended on the
use of a revolving cylinder in which the cryolite and sodium
reacted, and appears more chimerical than Netto's other pro-
positions. This latter device, however, is said to have been
operated at Essen.
32 ALUMINIUM.
In June, 1888, the Alliance Company were located at King's
Head Yard, London, E. C, and several small reduction furnaces
were being operated, each producing about 50 lbs. of alumin-
ium a day, estimates of the cost at which it was made giving
6 to 8 shillings per pound. In the early part of 1889 the
" Alkali Reduction Syndicate, Limited," leased ground at Hep-
burn on which to erect works for making sodium by Cunning-
ham's patents, the sodium produced being sent to Wallsend,
near Newcastle-on-Tyne, where the Alliance Company's reduc-
tion works were located.
In 1890 this company could not profitably compete with the
electrolytic processes, and in 1 892 their works were sold at auc-
tion.
Ludwig Grabau, of Hanover, Germany, has made several
patented improvements in producing aluminium, which are in
the same direction as Prof. Netto's methods. Mr. Grabau be-
lieves that in order that aluminium may possess its most valuable
qualities, either for use alone or in alloying, it should be of
almost chemical purity, and as the best means of attaining this
end economically he has improved the sodium method on
these three lines : —
1st. Production of cheap pure aluminium fluoride.
2d. Production of cheap sodium.
3d. Reduction in such a manner that no possible impurities
can enter the reduced metal, and that the sodium is completely
utilized.
Mr. Grabau has devised processes for making pure alumin-
ium fluoride from kaolin, sodium by electrolysis of fused salt,
and has succeeded in producing some very pure aluminium,
but not cheaply enough to compete with the Hall and Heroult
processes.
Col. William Frishmuth, of Philadelphia, operated a small
chemical works, and before i860 made sodium by Deville's
process, and with it made aluminium in small quantities. He
claimed to have other methods of producing aluminium cheaply,
but none of them were practicable. He deserves credit for hav-
HISTORY OF ALUMINIUM. 33
ing made a good casting of the aluminium tip on tlie Wasiiing-
ing Monument at our national capital.
In 1889 the aluminium industry was finely represented at the
Paris Exposition. It was the period in which the sodium pro-
cesses were at their culmination, and the electrical processes
just becoming serious competitors. A detailed account of the
exhibits reads as follows :
Societe Anonyme pour I'lndustrie de 1' Aluminium : In a
large case, the frame of which was aluminium bronze, samples
of aluminium, ferro-aluminium, aluminium bronze, forged and
rolled, and numerous articles of the latter alloy. Cowles Elec-
tric Smelting and Aluminium Company : Samples of ferro-alu-
uminium, aluminium bronze and aluminium brass of various
grades, aluminium silver, and numerous useful articles made of
these alloys. Brin Bros. : Samples of aluminium with thin iron
and steel castings made by its use. The Alliance Aluminium
Company:. Two large blocks of aluminium, cast hollow, weigh-
ing possibly 1,000 pounds and 500 pounds, respectively. The
inclosing balustrade and decorations were principally of alu-
minium or aluminium bronze. The Aluminium Company,
Limited : A solid casting of aluminium bronze weighing y^ ton,
and on this a solid block of 98 per cent, aluminium weighing
the same. In the corners of the case piles of ingots of 99 per
cent, aluminium, 10 per cent, bronze, 5 per cent, bronze, 10
per cent, ferro-aluminium, and 20 per cent, aluminium steel.
Besides which were a 7-inch bell, springs, statues, aluminium
plate, round and square tubes, wire, sheet, etc. Such were the
aluminium exhibits, which attracted as much interest as the
historic ingot of 1855 did at its debut, and, not taking into ac-
count that Mr. Hall's process was not represented and that the
German makers were debarred from exhibiting because of in-
ternational pique, yet the exhibit shown was one which demon-
strated the great advances made in the previous five years.
Since 1 890, the progress of the aluminium industry has been
steady but sure. The sodium processes have dropped alto-
gether from the race, and the electrical processes occupy the
3
34 ALUMINIUM.
field. Among these, the processes producing alloys only have
dropped out of sight. Among those that remain, only those
favorably situated, near abundant water power and with cheap
supplies of alumina, have flourished. The industry has reached
a strict commercial basis, in which every cent of cost has to be
considered, and every item of expense reduced to a minimum.
In 1890 the Cowles Electric Smelting and Aluminium Com-
pany began selling pure aluminium. They were sued by the
Pittsburgh Reduction Company for infringement of the Hall
patents, and in the early part of 1893 were enjoined by the
courts from continuing their pure-metal process, it being de-
clared an infringement of Hall's patents.
Mention should be made of the aluminium exhibit at the
Columbian Exposition in Chicago, 1893. The only makers
represented were the Pittsburgh Reduction Company, but their
exhibit was a very satisfactory representation of the state of the
art. A working model of an extraction pot was shown, hun-
dreds of pounds of the metal in all shapes and worked in every
way, a fine set of aluminium alloys, and several cases of manu-
factured goods made from their metal by various American
firms. Mr. Hirsh of Chicago showed aluminium electroplated
on other metals and on wood. The writer exhibited a metal-
lurgical suite showing the minerals from which aluminium is
extracted, samples of aluminium made by the various processes
which have been used, samples showing the physical properties
of the metal, its working, soldering, etc., and a large number of
its alloys.
The statistics about to be given will show graphically the
story of the rise of the aluminium industry. The last ten years
have witnessed an undreamt-of progress. Hereafter the lower-
ing in price can only be counted at a few cents a pound, but
the increase of production may be noted in thousands of tons.
A most fitting ending to this historical sketch would be simply
to repeat what I wrote three years ago, viz., " The nineteenth
century will live in history as that century which gave to the
world the railway, the telegraph, the telephone, the dynamo,
Bessemer steel and aluminium."
HISTORY OF ALUMINIUM. 35
STATISTICAL.
The following table shows the price at which aluminium has
been sold since it was first placed on the market :
Dale. Place. Per kilo. Per pound.
1856 (Spring) Paris looo fr. ^90.90
1856 (August) " 300 " 27.27
1859 " 200" 17-27
1862 " 130" 11.75
1862 Newcastle ii-75
1878 Paris 130" 11.75
1886 " 12.00
1887 Bremen 8.00
1888 London 4.84
1889 Pittsburgh 2.00
1891 " 1 1.50
1892 " i.oo
1893 " 0-75
1894 " 0.50
1895 Switzerland 3 M. 0.35
Until 1885 the selling price of aluminium bronze depended
directly on the price of aluminium, being about $1.50 per
pound for the ten' per cent, alloy. With the advent of the
Cowles and, later, the Heroult alloy-processes, the price fell
below what the contained aluminium would have cost, as is
shown by the selling price of the ten per cent, bronze, as fol-
lows:
Date. Place. Per kilo. Per pound.
1878 Paris 18.00 fr. gi.64
1885 Cowles Bros 4.50 " 0.40
1888 " " 3-85 " 0.35
1888 Heroult process, Neuhausen 3.30 " 0.30
Since 1889 the cost of the bronze has again been dependent
on the cost of the pure metal, so that no separate figures are
necessary, With copper at $0.10 per pound, and aluminium
at $0.50, the cost of 10 per cent, bronze is not over $0.20 per
pound.
As to the amount of aluminium which has been produced.
36 ALUMINIUM.
we can make the following estimates, gleaned from various
sources :
France.
Kilos.
1854-56 Deville 25
1859 Nanterre (Deville) 720
1859 Rouen (Tissier Bros.) 960
1865 France 1,090
1869 " 455
1872 Sallndres (H. Merle & Co.) 1,800
1882 " " " 2,350
1884 " " " 2,400
1887 France 3,500
1888 " 4,500
1889 " 14,840
1890 " 37,°oo
1891 " 36,000
1892 " 40,000
A careful estimate of the total amount made in France by
the Deville process, from 1855 to 1888, places it at 43,000
kilos. Since 1888, there has been made by other processes
128,000 kilos up to the year 1893, making a total of 171,000
kilos, or 375,000 pounds.
England.
Pounds.
1872 Bell Bros 1,650
1889 Castner process 50,000
1891 Electrolytic processes 90,000
1892 " " 90,000
The total English production up to 1890 was probably not
over 70,000 pounds. The Castner process produced altogether
from July, 1888 to 1891, 250,000 pounds. The total produced
in England to the end of 1 892 is therefore in the neighborhood
of 450,000 pounds.
Switzerland.
Kilos.
1890 Neuhausen 40,540
1891 " 168,670
1892 " 300,000
1893 " 480,000
1894 •' 600,000
HISTORY OF ALUMINIUM. 37
The total production of these works to the end of 1894 was
over 1,500,000 kilos, or 3,300,000 pounds.
United States.
Pounds.
1883 Frishmuth 70
1884 " 125
1885 " 230
1885 Cowles Bros, (in alloys) 450
'886 " " 6,500
•887 " " 17,800
1888 Pure and alloyed 19,000
1889 " 47,468
1890 " 61,281
1891 " 150,000
1892 " 259,885
1893 " • 333,629
1894 '• 706,000
World's Production to End of 1892.
Kilos. Pounds.
France 171,000 376,000
England 204,500 450,000
Switzerland 500,000 1,100,000
Germany (1885- 1 889) 50,000 110,000
United States 250,000 550,000
Total 1,175,500 2,586,000
The amount made in 1 893 was as follows :
France (estimated) 40,000 kilos.
Switzerland 480,000 "
United States 150,000 "
Total 670,000 " =: 1,474,000 pounds.
An estimate for 1 894 would be as follows :
France 100,000 kilos.
Switzerland 600,000 "
United States 320,000 "
Total 1,020,000 " = 2,244,000 pounds.
The total amount of aluminium made from 1855 to the be-
38 ALUMINIUM.
ginning of 1895 is, therefore, in the neighborhood of 2,865,500
kilos, or 6,304,000 pounds, while the annual production has
reached 1,000 long tons, and will probably be increased during
1895 to nearly 2,000 tons.
In comparing these figures with the production of other
metals, it is important to bear in mind the low specific gravity
of aluminium. For most practical applications, the bulk of the
metal used is a fixed quantity, and 1,000 tons of aluminium
are equal in volume to
4,600 tons of lead.
4,000 " " silver.
3,500 " " nickel.
3,300 " " copper.
2,800 " " tin.
2,700 " " zinc.
CHAPTER II.
OCCURRENCE OF ALUMINIUM IN NATURE.
There is no other useful metal, iron not excepted, which
is so widely scattered over the earth and occurs in such
abundance. F. W. Clarke of the Smithsonian Institution has
calculated that the percentage of aluminium in the earth's crust,
as far as it is known to us, is 7.81, while that of iron, the next
most abundant element, is 5.46.
Aluminium is not found metallic. Stocker * made the state-
ment that aluminium occurred as shining scales in an alumina
formation at St. Austel, near Cornwall, but he was in error.
But the combinations of aluminium with oxygen, the alkalies,
fluorine, silicon, and the acids, etc., are so numerous and occur
so abundantly as not only to form mountain masses, but to be
also the bases of soils and clays. Especially numerous are the
combinations with silicon and other bases, which, in the form
of feldspar and mica, mixed with quartz, form granite.
These combinations, by the influence of the atmospheric air
and water, are decomposed, the alkali is replaced or carried
away, and the residues form clays. The clays form soils, and
thus the surface of the earth becomes porous to water and
fruitful. It is a curious fact that aluminium is rarely found in
animals or plants. According to Church, f alumina is found
only in a few vascular cryptogamous plants, whose ash con-
tains up to 20 per cent.
Ricciardi concluded from numerous experiments that the
assimilation of alumina by plants does not depend upon the
abundance of alumina in the soil, and that, generally speaking,
* Joum. fr. prakt. Chem., 66, 470.
t Proc. Royal Society, Vol. 44, p. 121.
(39)
40 ALUMINIUM.
there is more found in the trunk and branches, less in the
husks and seeds, and least in the leaves.
Most of the aluminium compounds appear dull and disagree-
able, such as feldspar, mica, pigments, gneiss, amphibole, por-
phyry, eurite, trachyte, etc. ; yet there are others possessing
extraordinary lustre, and so beautiful as to be classed as prec-
ious stones. Some of these, with their formulae, are :
Ruby AI2O3
Sapphire Al^Oj
Garnet (Ca.Mg.Fe.Mn)3Al2Si30,2
Cyanite AUSiOj
Some other compounds occurring frequently are :
Turquoise AljPPs.HjAljOs.aHjO
Lazulite (MgFe)AljP203 -|- Aq
Wavellite 2AI2P2O8.H1.AI2O6.9H2O
Topaz 5AL,Si05.Al,SiFi„
Cryolite Al^Fg.eNaF
Diaspore AIJO3.H2O
Bauxite AI2O3.2H2O
Aluminite AlaSOe.gH^O
Alunite K^s6i.Al^Sfi,^.2H^Alfii
Soda Feldspar NajAl2Si60ig
Potash Feldspar KjAljSigOjj
Lime Feldspar CaAljSijOg
Kaolin Al2SijO,.2H20
Bauxite and cryolite are the minerals most used for produc-
ing aluminium, and their preference lies mainly in their purity.
Native alums generally occur in out of-the-way places and not
in beds of very large extent.
Bauxite.
Bauxite is a hydrous aluminium oxide of variable composi-
tion, sometimes approaching diaspore in its proportion of water,
but with the aluminium always more or less replaced by iron,
and some silica disseminated through it. Its color is creamy
white when free from iron, and its structure usually pisolitic,
that is, in small globules like peas. It was first found in
OCCURRENCE OF ALUMINIUM IN NATURE. 4 1
France, near the town of Baux, large deposits occurring in
the departments of Var and Bouches du Rhon, extending from
Tarascon to Antibes. Several of these beds are a dozen yards
thick, and sixteen kilometers in length. Deposits are also
found in the departments of I'Herault and I'Arriege. Very im-
portant beds are found in Styria, at Wochein, and at Freis-
stritz, in Austria, a newly discovered locality where the mineral
is called Wocheinite. Here it has a dense, earthy structure,
while that of France is conglomerate or oolitic. Deposits
similar to those of France are found in Ireland at Irish Hill,
Straid, and Glenravel. Further deposits are found in Hadamar
in Hesse, at Klein Steinheim, Langsdorff, and in French
Guiana.
In the United States large beds have been found in Alabama,
Georgia, and Arkansas. Those of Georgia have been worked
since 1890, and are now affording a large part of all the
bauxite consumed in this country. The deposits of the Coosa
Valley in Georgia and Alabama are worked by three com-
panies, the Republic Mining and Manufacturing Company, the
Georgia Bauxite and Mining Company, and the Southern
Bauxite Mining and Manufacturing Company. These three
companies produced, in 1893,9,200 tons, which was three-fifths
of the total bauxite consumed in the United States, the rest
being imported from Ireland. The ore is found in beds or
pockets, and while the quantity in sight is not inexhaustible,
yet there is sufficient for many years to come, at the pres-
ent rate of mining. These bauxites are as pure as those
of Europe, and the manufacturers using them say they are
more easily worked and so prefer them to the imported, even
though they often carry less alumina and cost more. The
Arkansas ore occurs in tertiary formations, in irregular de-
posits of 5 to 40 feet in thickness, not over 300 feet above tide
water. H. L. Fletcher, of Little Rock, owns much of the land
on which they occur.
The cost of imported bauxite is $5 to $7 a ton ; of Ameri-
can bauxite $5 to 12 per long ton, according to where the
42
ALUMINIUM.
market is; best selected Georgia bauxite brings $io per ton
in New York city.
The following are analyses of foreign bauxites ; besides the
ingredients given there are also traces of lime, magnesia, sul-
phuric, phosphoric, titanic and vanadic acids.
Alumina ■ • ■
Ferric oxide
Silica
Alkalies. • . .
Water
60.0
25.0
3-°
12.0
75.0
12.0
i.o
12.0
3
4
63.16
72.87
23-SS
13-49
4.15
4.25
0.79
0.78
8-34
8.50
44.4
30-3
15.0
9-7
6
54.1
10.4
12.0
29.9
Alumina ■ ■ .
Ferric oxide
Silica
Alkalies . ■ -
Water
Alumina • • •
Ferric oxide
Silica
Alkalies
Water
7
64.6
8
9
48.12
10
II
61.89
29.80
43-44
2.0
3.67
2.36
2.1 1
1.96
7-5
44.76
7-95
'5-°5
6.01
24.7
13-86
40-33
35-7°
27.82
13
SS-6I
7.17
4.41
32-33
14
76.3
6.2
1 1.0
26.4
15
50.85
14.36
5.14
0.26
28.38
16
49.02
12.90
10.27
0.31
25-91
45-76
18.96
6.4 1
0.38
27.61
73.00
4.26
2.15
18.66
Index: —
I and 2. From Baux (Deville).
Dark \
T ■ vj ]■ Wocheinite (Drechsler).
Red brown \
Yellow >■ Bauxite from Freisstritz (Schnitzer).
White >
White Wocheinite (L. Mayer and O. Wagner).
Bauxite from Irish Hill.
OCCURRENCE OF ALUMINIUM IN NATURE.
43
10. Bauxite from Co. Antrim (Spruce).
11. « " Glenravel (F. Hodges).
12 and 13. " " Hadamar in Hesse (Retzlaff).
14. From Klein-Steinheim (Bischof).
15 and 16. From Langsdorfi (I. Lang).
17. Bauxite from Dublin, Ireland, brought to the Laurel Hill Chemical
Works, Brooklyn, L. I., and there used for making alums. It is dirty
white, hard, dense, compact, and in addition to the ingredients given
above contains 0.59 per cent, of lime and some titanic acid. It costs
$6 per ton laid down in the works. The above analysis, made by Mr.
Joiiet, is furnished me by the kindness of the superintendent of the
works, Mr. Herreshoff.
The American bauxites are fully equal to the foreign in
quality, as is shown by the following analyses :
Ferric Oxide.
Silica
Water
Titanic Acid.
18
Alumina | 37-62
1.83
11.48
28.63
19
55-59
6.08
10.13
28.99
20
21
22
46.44
58-60
46.72
22.15
9.II
2.14
4-89
3-34
29.01
26.68
28.63
20.15
—
—
0.87
Alumina —
Ferric Oxide
Silica
Water
Titanic Acid
58.61
2.63
8.29
27.42
3-15
24
67-53
trace
1-34
28.00
2.92
25
60.61
0.21
2-47
32.00
4.18
26
61.87
2.38
0.40
30.50
27
40-93
22.60
8-99
20.43
18. Little Rock Region, Pulaski Co., Arkansas.
jg >I « " " "
20. Red variety. Saline Co., Arkansas.
21. Pink "
22. White variety, Floyd Co., Georgia.
2j-
24. Georgia Bauxite Company.
2c " " "
26. Wharwhoop Mine, Cherokee Co., Alabama.
27. Red variety, Cherokee Co., Alabama.
44 ALUMINIUM.
Regarding French bauxites, Francis Laur, the first to work
the French deposits, states* that one of their peculiarities is
that the bulk of that mined contains a nearly constant amount
of alumina, of silica, ferric oxide and water taken together, and
of other impurities. The proportions are very nearly
Alumina 68 to 70 per cent.
Silica, ferric oxide and water 27 "
Other impurities 3 to 4 "
In the bauxite from Baux, that first worked, the silica, ferric
oxide and water are present in about equal proportions ; that
is, about 8 to 10 per cent, of each. In the pale bauxite from
Villeveyrac (Herault) there is almost no iron, and the 27 per
cent, is nearly evenly divided between silica and water ; what
small amount of ferric oxide does occur in it can be put into
the list of " other impurities." The red bauxite, discovered in
1880 in the south of France, is very constant in composition,
and may be regarded as the inverse of the pale variety. In this
red kind the silica is so small as to be relegated to the acces-
sory constituents, while water and ferric oxide alone make up
the 27 per cent. These three varieties represent the three types
of bauxite which are mined in large quantities. The pale
variety, being low in iron, is preferred for making aluminium
sulphate by treatment with sulphuric acid, which attacks it very
readily; the red kind is preferred for the sodium carbonate
treatment, as the iron does not interfere, while silica is kept out
of the alumina produced. Besides these kinds, some varieties
are found with the 27 per cent, either all water, all silica or all
ferric oxide. We would thus have, as the composition of the
typical kinds of bauxite found in France, the following:
Water. Silica. Ferric oxide.
Hyaline bauxite 27 o o
Silicious type, compact o 27 o
Ferruginous type, in pisolites o o 27
Red bauxite of Var 131^ o 131^
Pale bauxite of Villeveyrac 131^ i^}4 o
Mixed bauxite of Baux 9 9 9
* Trans. Am. Inst. Mining Eng., Feb., 1894.
OCCURRENCE OF ALUMINIUM IN NATURE. 45
Mr. A. E. Hunt, of Pittsburgh, in the discussion of this paper,
remarked that there are vast quantities of bauxite in Georgia,
Alabama and Arkansas, which run low in both silica and ferric
oxide, containing less than 5 per cent, of both these ingredients,
but with about 4.5 per cent, of titanic acid. It is his experience
that when the water of hydration is below 31 per cent., in the
greyish and white bauxite from Georgia and Alabama, the
silica is always high. If the bauxite is red, however, the water
may be low without the silica being high. He cites the follow-
ing analyses illustrating this point :
Combined water.
Silica.
Ferric oxide.
Titanic acid.
Alumina,
33-43
0.80
0.47
4.20
61.10
32.00
2.66
0.47
4.06
60.81
20.93
22.96
0.47
4.72
51.14
16.70
32-03
0.71
3-76
47-03
18.20
3.10
17-3°
3-9°
57.00
It will be seen that Mr. Laur's generalizations regarding
French bauxites do not hold good for the American varie-
ties ; the constancy of the titanic aci,d is also remarkable.
Cryolite.
Cryolite was first found at Ivigtuk in Arksut-fiord, west coast
of Greenland, where it constitutes a large bed or vein in gneiss.
It was very rare even in mineralogical collections until 1855,
when several tons were carried to Copenhagen and sold under
the name of " soda mineral." It is a semi-transparent, snow-
white mineral. When impure it is yellowish or reddish, even
sometimes almost black. It is shining, sp. gr. 2.95, and hard-
ness 2.5 to 3. It is brittle, not infrequently contains ferrous
carbonate, sulphide of lead, silica, and sometimes columbite.
It is fusible in the flame of a candle, and on treatment with
sulphuric acid yields hydrofluoric acid. As will be seen further
on, cryolite was first used by the soap-makers for its soda ; it
is still used for making soda and alumina salts, and to make a
white glass which is a very good imitation of porcelain. The
Pennsylvania Salt Company in Philadelphia import it from
4-6 ALUMINIUM.
Ivigtuk by the ship-load for these purposes ; lately they have
discontinued making the glass. Cryolite is in general use as a
flux. A very complete description of the deposit at Ivigtuk
can be found in Hoffman's " Chemische Industrie."
Pure cryolite contains
Aluminium l3-°
Fluorine 54-5
Sodium 32.5
100.00
Or otherwise stated,
Aluminium fluoride 40.25
Sodium fluoride ■* 59-75
100.00
From the reports in the Mineral Resources of the United
States we find that there was imported by the Pennsylvania
Salt Company in 1892, 8000 long tons, which was valued at
$9 a ton. The importers say this value is too low ; they sell
what they call pure prepared cryolite at $60 a ton. This so
called pure article was found by Prof. Rogers, of Milwaukee, to
contain two per cent, of silica and one per cent, of iron ; in
fact, the whitest cryolite always contains silica microscopically
disseminated through it, which cannot be separated out by any
means.
The only known deposit of cryolite in the United States is
that found near Pike's Peak, Colorado, and described by W.
Cross and W. F. Hillebrand in the "American Journal of
Science," October, 1883. It is purely of mineralogical import-
ance and interest, occurring in small masses as a subordinate
constituent in certain quartz and feldspar veins in a country
rock of coarse reddish granite. In composition, however, it is
practically identical with the Greenland cryolite, so that the
following analysis by Mr. Hillebrand will stand for a typical
analysis of cryolite as found in nature :
OCCURRENCE OF ALUMINIUM IN NATURE. 47
Fluorine 53.55 per cent.
Aluminium , 12,81 "
Sodium 32.40 "
Ferric Oxide 0.40 "
Lime 0.28 "
Water 0.30 "
Corundum.
Until 1869 the sole sources of corundum were a few river
washings in India and elsewhere, where it was found in scat-
tered crystals. Its cost was twelve to twenty-five cents a
pound. Within the last twenty years numerous mines have
been opened in the eastern United States, the first discovery of
which was due to Mr. W. P. Thompson, and is thus described
by him : *
" In 1869, in riding over a spur of the Alleghenies in north-
ern Georgia, I found what has proven to be an almost inex-
haustible mine of corundum in the chrysolite serpentine, the first
instance on record of the mineral being found. /« situ. Previ-
ously it had been washed out of debris at Cripp's Hill, N. C,
and at a mine in West Chester, Pa., both on the slopes of the
chrysolite serpentine. The clue being thus obtained accident-
ally, about thirty mines were shortly afterwards discovered in
the same formation ; but of the thousands of tons thus far dug
out, the larger portion has come from the mines I discovered.
" At present it can be bought at about ten dollars per ton at
the mines. It is nearly pure alumina. Disapore, a hydrated
alumina, is also found in the same region and locality. Corun-
dum will probably always be the principal source in America
of material from which to manufacture pure aluminium ; but in
Great Britain, in all probability, manufacturers must look to
alumina prepared artificially from cryolite or from sulphate of
alumina."
In 1892 the production of corundum in the United States
was somewhat over 2000 short tons, valued at $40 a ton when
sifted and broken to proper sizes for the market, the Hamp-
* Journal of the Society of Chemical Induustry, April, 1886.
48 ALUMINIUM.
den Emery Company, at Laurel Creek, Ga., and at Corundum
Hill, N. C, and the Unionville Corundum Mines Company, at
Unionville, Chester Co., Pa., being the principal producers.
Thus, while corundum may be worth in bulk at the mines only
$io a ton, yet it is extremely hard to crush, and when broken
up fine is worth far more as an abrasive than as an aluminium
ore. The present large development of bauxite mining has
completely nullified the use of corundum as a source of alumin-
ium, and I do not suppose that at present a single pound of
aluminium is being made from it.
Kaolin.
The mineral kaolin is variously known as white china clay,
fuller's- earth, or pure white clay. It is essentially a hydrated
silicate of aluminium, containing when pure
Alumina 39.8 per cent.
Silica 46.3
Water 13.9 "
Its chemical formula is Al2O3.2SiO2.2H2O. If the water is
driven off by calcination, the residue contains 46.2 per cent.
of alumina, or 24.4 per cent, of aluminium.
Kaolin has been formed mostly by the atmospheric decom-
position of feldspar, the alkalies of which are changed into
carbonates by the carbonic acid of the rain water, and are then
leached out, carrying with them part of the silica in solution,
and leaving kaolin, according to the reaction,
K2Al2Si60,6f2H20+C02=Al2SiA.2H20+K2C03-t-4Si02.
Kaolin acquires a certain plasticity when mixed with water.
Hydrochloric and nitric acids have no action on it, but cold
sulphuric acid dissolves its alumina, setting the silica at liberty.
It is infusible unless contaminated with particles of feldspar or
calcium sulphate, carbonate, or phosphate. The specific gravity
of kaolin is 2.3. If fused with six times its weight of caustic
potash, the resulting mass gives up potassium aluminate when
OCCURRENCE OF ALUMINIUM IN NATURE. 49
washed with water, An analogous result is obtained with
sodium carbonate. Grabau has prepared very pure aluminium
fluoride from kaolin by the use of sulphuric acid and subse-
quent boiling with fluorspar.
Large deposits of kaolin are found in many parts of the
world. The best locality in Europe is near Limoges, France,
with which the famous Sevres porcelain is made. Large beds
are found in Cornwall and West Devon, England. In the
United States the largest deposits are at Wilmington, Del., and
in South Carolina, Georgia and Alabama. These deposits are
worked extensively, and the product used by the pottery,
paper, cotton, and various other industries. The value at the
mines is very small, it not costing over $0.50 per ton to mine
it, but for many purposes it must be crushed, washed, and even
floated, which increases its value to $5 or $10 a ton in New
York city.
The purity of kaolin, and the almost inexhaustible beds in
which it occurs, stamp it as the natural ore of aluminium. All
that is needed is a cheap process for separating the pure alu-
mina from the silica, in which case no other mineral could
compete with it as the main staple of the aluminium industry.
This is a promising field for chemical experimenters, for such
a process would be of great value.
Common clays are either very impure kaolin, or else they
contain chemically a much larger proportion of silica. The
percentage of silica may range from 50 per cent, up to 70 per
cent, while that of the alumina present ranges downwards from
35 to 15 per cent. These common clays are far too impure
and low in silica to serve as a source of aluminium, and in no
case could they compete with kaolin.
Some anhydrous silicates of aluminium are found in nature,
such as Disthene, Andalusite and Cyanite, whose formula is
AUOj.SiOj, containing 62.5 per cent, of alumina ; but they do
not occur in large quantities, and, even if they did, are so hard
and difficult to decompose that they would never be preferred
to kaolin.
4
50 aluminium.
Native Sulphate of Alumina.
In the summer of 1884, a large deposit of rock called " native
alum" was discovered on the Gila River, Socorro County, New
Mexico, about two miles below the fork of the Little Gila, and
four miles below the Gila Hot Springs. The deposit is said to
extend over an area one mile square and to be very thick in
places. The greater part of the mineral is impure, as is usual
with native occurrences, but it is thought that large quantities
are available. A company formed in Socorro has taken up the
alum-bearing ground. Through the kindness of Mr. W. B.
Spear, of Philadelphia, the author was enabled to get a speci-
men of the mineral.
It is white, with a yellowish tinge. On close examination it
is seen to consist of layers of white, pure-looking material ar-
ranged with a fibrous appearance at right angles to the lamina-
tion. These layers are about one-quarter of an inch thick.
Separating them are thin layers of a material which is deeper
yellow, harder and more compact. The whole lump breaks
easily, and has a strong alum taste. On investigation, the
fibrous material was found to be hydrated sulphate of alumina,
the harder material sulphate of lime. Analysis showed 7 to 8
per cent, of insoluble material, the remainder corresponding to
the formula Al2(S04)3.i8H20. A small amount of iron was
present.
State Geologist Waring informs the writer that the deposits
occur only in sheltered spots protected from the rain, that the
region is eruptive, and that where the trachyte rock is being
decomposed by sulphuric gases and waters, the salts rise to the
surface and form crusts in protected places. Often the earth
contains 10 per cent, or more of the anhydrous sulphate.
A similar mineral occurs in Purgatory Valley, 12 miles east of
Trinidad, Colorado.
A variety of the same mineral containing some silica was
found in a stratum 25 feet thick by the Congo Coal Company,
while sinking a shaft at Congo, Ohio, in 1893. An analysis of
this by Dr. Lisle, of Springfield, Ohio, gave
OCCURRENCE OF ALUMINIUM IN NATURE. Si
Alumina 50.16 per cent.
Silica 28.98 "
Lime 0.46 "
Sulphuric acid 16.21 "
Water 4.28 "
These minerals would appear to ofifer a cheap source of
alumina, as the operations necessary for treating them are very-
simple, being solution in warm water, filtration, evaporation,
and roasting. The excessive freight charges are against the
New Mexico and Colorado deposits, but that in Ohio should
be of considerable economic importance if the reports concern-
ing its extent are verified.
CHAPTER III.
PHYSICAL PROPERTIES OF ALUMINIUM.
Commercial aluminium is never chemically pure, and there-
fore displays properties varying more or less from those of the
pure .metal according to the character and amount of impurities
present. In this treatise, whenever the properties of aluminium
are mentioned, they must be understood to refer to the chemi-
cally pure metal, and not to the commercial article, unless spe-
cifically stated.
The impurities most frequently present in commercial alu-
minium are iron and silicon. These are found in all brands,
varying in amount from i per cent, in the purest to 6 and even
8 per cent, in the worst. Besides these, various other impuri-
ties are found coming from accidental sources in the manufac-
ture ; thus, some of the first metal made by Deville contained
a large amount of copper (Analysis i), coming from boats of
that metal which he used in his experiments. Metal made
later by Deville contained zinc, coming from zinc muffles which
he had borrowed and used for retorts, old retorts broken up
having been used in the composition of the new ones. More
recently, aluminium has been produced by the agency of
sodium in the presence of lead, which latter it takes up in small
amount. Sodium is liable to remain alloyed in very small pro-
portion, yet it is an element so easily attacked that it destroys
some of the most valuable qualities of the aluminium. The
distinct effect, however, of each of these usual impurities in
modifying the physical properties of aluminium has not yet
been investigated in a thoroughly satisfactory manner. A few
years more, however, of increasing familiarity with and hand-
ling of the metal on a large commercial scale will, I believe,
(52)
PHYSICAL PROPERTIES OF ALUMINIUM. S3
cause the effect of foreign elements on aluminium to be as
plainly recognized as is now the case with carbon and the
metalloids in iron. In general, we may say that silicon seems
to play a role in aluminium closely analogous to that of carbon
in iron ; the purest aluminium is fibrous and tough, but a small
percentage of silicon makes it crystalline and brittle. Further-
more, a considerable proportion occurs in the graphitoidal
state, and may be separately estimated as graphitoidal silicon
by dissolving the metal in dilute hydrochloric acid in the pres-
ence of bromine water. A small amount of silicon, however,,
gives pure aluminium a bluish cast, a disagreeable smell, and
greatly lessens its resistance to corroding agents. A small
proportion of iron makes the metal denser and stronger, but a
quantity above i per cent, quickly makes it brittle. A small
quantity of copper whitens aluminium, makes it much stronger
and lessens its shrinkage in casting, but with over 5 per cent,
it becomes brittle.
As aluminium was made by the sodium processes, it con-
tained as impurity about equal quantities of iron and silicon ; as
made by the electrolytic processes, the iron present is usually
much less than the silicon. Carbon can only exist in alumin-
ium that has been subjected to an intense heat, such as in an
electric furnace, when it may be absorbed in small quantity,
and makes the metal brittle ; it does not occur, however, in
ordinary commercial aluminium. Titanium may occur in
aluminium made from raw bauxite, which frequently contains
titanic oxide ; its presence in small amount makes the metal
much stronger, but gives it a bluish tint. There is needed a
systematic investigation of the effect of small amounts of impuri-
ties on the physical and chemical properties of pure aluminium.
The following analyses are of considerable historic interest as
showing incidentally the improvement which has been made in
the quality of the commercial metal since the beginning of the
industry :
54
ALUMINIUM.
Aluminium.
1. Deville Process 88.350
2. " " 92.500
3. " " 92.000
4. " " 92.969
5. " " 94-700
6. " " 96.160
7. Tissier Bros 94.800
8. Morin & Co., Nanterre 97.200
9. " " 97.000
10. " " 98.290
11. " " 97.680
12. Merle & Co., Salindres 96.253
13. " " 96.890
14. " " 97-400
15. " " 97.600
16. Frishmuth 97-49
17- " 97-75
18. Hall's Process 98-34
19. Deville-Castner - . 99.20
20. Grabau Process 99.62
21. " " 99-So
22. Hall's Process 99-93
Silicon.
Iron.
2.87
2.40
0.70
6.80
0.45
7-55
2.149
4.88
3-70
1.60
0.47
3-37
4.40
0.80
0.25
2.40
2.70
0.30
0.04
1.67
0.12
2.20
0.454
. 3-293
1.270
1.840
1. 00
1.30
0.40
1.40
1.90
0.61
1.70
0.55
1-34
0.32
0.50
0.30
0.23
0.15
0.12
0.08
0.07
trace.
Notes on the above analyses :-
2
and
3-
4-
5-
7-
8.
9-
[O,
II.
12, 13.
14. 15-
16.
Analyzed by Salvetat. Contained also 6.38 per cent, of copper and a trace
of lead.
Analyzed by Dumas.
Parisian aluminium bought in La Haag,
Analyzed by SalvStat. Contained also a trace of sodium.
Parisian aluminium bought in Bonn and analyzed by Dr. Kraut.
Made at the works near Rouen, in 1858, from cryolite. Analyzed by
Demond^ur.
Analyzed by Sauerwein. Contained also traces of lead and sodium.
Analyzed by Morin. Average of several months' work.
Analyzed by Kraut. Represents the best product of the French works
sent to the London Exhibition in 1862.
Analyzed by Mallet. The best metal v/hich could be bought in 1880.
Purchased in Berlin by Mallet, and used by him as the material which
he purified and used for determining the atomic weight of aluminium.
Analyzed by Hampe. This was the purest metal which could be bought
in 1876. No. 14 contained also o.io per cent, of copper and 0.20 per
cent, of lead. No. 15 contained 0.40 per cent, of copper and 0.20 per
cent, of lead.
Bought in Philadelphia as Frishmuth's aluminium, in 1885, and analyzed
by the author.
PHYSICAL PROPERTIES OF ALUMINIUM. 55
17. Specimen of the metal composing the tip of the Washington Monument,
cast by Frishmuth. This analysis is reported by R. L. Packard m the
Mineral Resources of the United States, 1883-4.
18. The best ordinary grade of metal made by this process, analyzed by Hunt
& Clapp, Pittsburgh. For average analyses, etc., see description of pro-
cess.
19. The best grade made by this process, exhibited at the Paris Exposition,
1889. Analyzed by CuUen.
20. Analysis by Dr. Kraut of metal being made on a commercial scale.
21. Analysis by Grabau of the purest metal yet obtained by his process.
22. Made from chemically pure alumina, in order to determine what degree of
purity was attainable by the electrolytic processes.
In addition to the above, the following analyses made in the
Pittsburgh Testing Laboratory show the quality of commercial
aluminium which has been put on the market in recent years :
Com- Graphi-
Alumin- bined toidal
Second Quality Metal. ium. Silicon. Silicon. Iron. Copper. Sodium. Lead.
Pittsburgh Reduction Co 9S-00 1.50 1.35 2.00 0.07 0.04 0.03
Society Anon, de TAluminium .. 95.00 0.90 i.oo 3.00 0.05 o.oi 0.04
Alliance Aluminium Co 95-00 0.90 0.75 3.25 0.02 0.07 o.oi
The Aluminium Co., Limited . . . 95.00 0.85 0.75 3.00 o.io 0.30 nil
The Al. LA. G., Switzerland ... 95.00 1.75 1.15 2.00 o.ci 0.07 nil
" " " ... 94.15 1.02 0.54 2.80 1.49 — —
First Quality Metal.
Pittsburgh Reduction Co 97.00 1.55 1.25 0.13 0.03 0.02 0.02
Soc. Anon, de I'Al 97.00 0.90 0.82 1.20 0.04 o.oi 0.03
Alliance Al. Co., Ltd 97.00 0.95 0.53 1.45 0.01 0.05 o.oi
The Al. Co., Limited 97.00 0.75 0.52 1.55 0.03 0.15 nil
Pittsburgh Reduction Co 98.00 1.30 0.60 0.07 o.oi o.oi o.oi
Soc. Anon, de I'Al 98.00 0.71 0.35 0.90 o.oi o.oi 0.02
Alliance Al. Co., Ltd 98.00 0.90 0.29 0.75 o.oi 0.04 o.oi
The Al. Co., Limited 98.00 0.90 0.23 0.80 0.02 0.05 nil
Pittsburgh Reduction Co 98.52 0.42 0.72 0.05 0.06 nil 0.04
" " " 99.00 0.80 0.15 0.03 O.OI nil O.OI
Soc. Anon, de I'Al 99-00 0.35 0.13 0.50 nil o.oi o.oi
Alhance Al. Co., Ltd 99.00 0.31 0.20 0.45 nil 0.03 o.oi
The Al. Co., Limited 99-°° °-^l °-'S o-5S °-°2 o.oi nil
Pittsburgh Reduction Co 99-20 041 0.34 0.05 nil nil nil
Alliance Al. Co., Ltd 99- H o-23 0.17 0.46 nil nil nil
Pittsburgh Reduction Co 99-34 °A° 0-21 0.05 nU nil nil
The makers represented above are :
The Pittsburgh Reduction Company. New Kensington, Pa.
56 ALUMINIUM.
The Alliance Aluminium Company, Limited. Wallsend-on-
Tyne, England.
The Aluminium Company, Limited. Oldbury, near Birming-
ham, England.
The Societe Anonyme de I'Aluminium. Nanterre, France.
The Aluminium Industrie Actien-Gesellschaft. Neuhausen,
Switzerland.
The second, third and fourth of these firms used the sodium
process, the others the electrolyic methods. It is at once seen
that for metal with the same proportion of aluminium, that
made by the electrolytic processes contains less iron, but more
silicon, than that made by the sodium processes ; there is no
observable regularity in the proportion of combined and graph-
itoidal silicon to the amount of iron. On an average, the graph-
itoidal silicon is about one-third to two-thirds of the combined
silicon.
Rammelsberg (Kerl's Handbuch) investigated the question
of the different states of silicon in aluminium. He found in
aluminium reduced from cryolite by sodium in a porcelain cru-
cible, that on treatment with hydrochloric acid, the combined
silicon changes into silica, or part escapes as silicon hydride,
while the graphitoidal silicon remains as a black residue. Two
analyses gave him the following results :
1.. 2.
Silicon obtained as silica 9.55 1.85
Free silicon 0.17 0.12
Silicon escaping in SiH'' 0.74 0.58
In aluminium containing 6.20 per cent, of total silicon, ana-
lyzed in the Pittsburgh Reduction Co.'s laboratory, 3.85 per
cent, was graphitoidal silicon. In another specimen, contain-
ing 5 -30 per cent, of total silicon, 2.40 per cent, was graphi-
toidal.
An experiment, made at the Pittsburgh Testing Laboratory,
to determine the influence of quick or slow cooling on the con-
dition of the silicon, showed that the chilled metal contained,
slightly more of the silicon in the graphitoidal state and less in
the combined state than metal slowly cooled.
PHYSICAL PROPERTIES OF ALUMINIUM. 57
This result is the opposite of the behavior of carbon in iron,
and it is found, as might be expected, that no appreciable dif-
ference in hardness can be detected between the surfaces of
ingots cast in chills and those cast in hot moulds.
M. Dumas found that aluminium usually contains gases,
about which he makes the following statements:* On submit-
ting aluminium in a vacuum to the action of a gradually increas-
ing temperature up to the softening point of porcelain, and
letting the mercury pump continue acting on the retort until it
was completely exhausted, considerable quantities of gas were
withdrawn. The liberation of the gas from the metal seems to
take place suddenly towards a red-white heat. 200 grammes
of aluminium, occupying 80 c.c, gave 89.5 c.c. of gas, meas-
ured at 17° and 755 mm. pressure. The gas consisted of 1.5
c.c. carbonic acid, and 88 c.c. hydrogen. Carbonic oxide,
nitrogen and oxygen, were absent.
The author has observed that molten aluminium will absorb
large quantities of gas. On passing sulphuretted hydrogen
into the melted metal for about twenty minutes some aluminium
sulphide was formed, while the metal appeared to absorb the
gas. On pouring, the metal ran very sluggishly, with a thick
edge, but when just on the point of setting, gas was disengaged
so actively that the crackling sound could be heard several feet
away, and the thick metal became suddenly quite fluid and
spread over the plate in a thin sheet. The gas disengaged
seemed by its odor to contain a large proportion of sulphur-
etted hydrogen, although free hydrogen may have been pres-
ent in it.
Le Verrier has established the presence of carbon in small
amount in commercial aluminium.! Taking a large quantity of
metal and treating it with a current of hydrochloric acid or
hydriodic acid gas, entirely free from oxygen, there remains a
grey residue. This, treated with dilute hydrochloric acid, gives
a very light residue of amorphous carbon, of a maroon color,
* Comptes Rendus, xc, 1027 (1880).
t Comptes Rendus, July, 1894, p. 14.
58 ALUMINIUM.
■which, on being separated out, can be entirely burnt to car-
bonic acid gas in a current of oxygen. This carbon does not
contain a trace of graphite ; it is entirely amorphous. It is
easiest estimated by dissolving ten grammes of aluminium in a
concentrated solution of caustic potash, washing the residue
with water, drying, burning in a current of oxygen, and weigh-
ing the carbonic acid formed. In three specimens tested there
were found 0.104, O.108 and O.080 per cent, of carbon respect-
ively. To determine the effect of carbon on the physical prop-
erties of aluminium, he melted best quality metal, cast a
specimen ingot, and then dissolved in it some crystallized
aluminium carbide, AhCs (for method of making this see Chap-
ter XIV) . A specimen of the carburized metal was then cast
and tested. The results were as follows; the weights being per
square millimetre of section :
Cast Specimens.
Elastic Limit. Breaking Load. Elongation.
Pure aluminium — 1 1. 1 kilos. 9 per cent.
Carburized aluminium — 6.5 " 5 "
— 8.6 " 3 "
Rolled Specimens.
Elastic Limit. Breaking Load. Elongation.
Pure aluminium, hard 23 kilos. 25.0 kilos. 2.0 per cent.
" " annealed 8 " 14.0 " 23.0 "
Carburized aluminium, hard 20 " 20.79 " 2.5 "
" " annealed 7.7 " 13.80 " 26.5 "
It would appear that the cast metal shows the greatest de-
terioration by the presence of carbon.
Le Verrier also proved the presence of traces of nitrogen in
commercial aluminium by passing the hydrogen evolved during
solution in dilute caustic potash into a Nessler solution, which
then gives the ammonia reaction. To determine the exact
effect of nitrogen, some aluminium was melted and a current of
nitrogen passed into it. The metal became saturated with the
gas, and showed the following diminution in strength :
PHYSICAL PROPERTIES OF ALUMINIUM. 59
Cast Specimens.
Elastic Limit, Breaking Load. Elongation.
Pure aluminium 7.5 kilos. i I.I kilos. 9 per cent.
Aluminium saturated with nitrogen 6.5 " g.6 " 6 "
Le Verrier considers that nitrogen and carbon occur in alu-
minium in the state of aluminium nitride and carbide re-
spectively, dissolved in the excess of aluminium. The same
investigator has discovfered by the microscope, in the residue
left by dissolving in hydrochloric acid, very small, sharp crys-
tals of boron carbide, the boron coming from the boric acid
used in agglomerating the carbon electrodes. A little amor-
phous alumina is also sometimes to be found.
Color.
Deville : The color of aluminium is a beautiful white with a
slight blue tint, especially when it has been strongly worked.
Being put alongside silver, their color is sensibly the same.
However, common silver, and especially that alloyed with
copper, has a yellow tinge, making the aluminium look whiter
by comparison. Tin is still yellower than silver, so that alu-
minium possesses a color unlike any other useful metal.
Mallet: Absolutely pure aluminium is perceptibly whiter
than the commercial metal ; on a cut surface very nearly pure
tin- white, without bluish tinge, as far as could be judged from
the small pieces examined.
The purest-looking aluminium examined by the author is
that made by Grabau. On a fresh fracture it is absolutely
■white, but on long exposure to the air it takes a faint, almost
imperceptible bluish tint. On a cut surface it has the faintest
suspicion of a yellow tint, not so decided as the yellowish color
of pure tin. Ordinary commercial aluminium is bluish on a
fresh fracture, the tint being deeper the greater the amount of
impurities it contains. A specimen with 10 per cent, of silicon
and 5 per cent, of iron was almost as blue as lead. It is my
belief that a very small percentage of copper closes the grain
-and whitens the fracture a little; I have also found that chilling
6o ALUMINIUM.
suddenly from a high temperature has the same effect. Wheir
ingots of aluminium are exposed a long time to damp air, the
thin film of oxide forming on them gives a more decided bluish
cast to the metal, since the coating is perfectly snow-white and
hence, by contrast, heightens the bluish tint of the metallic
background. Mourey recommended removing this discolora-
tion by placing the articles first in dilute hydrofluoric acid,
1,000 parts of water to 2 of acid, and afterwards dipping in
nitric acid. The oxide would thus be dissolved and the original
color restored. Pure aluminium possesses to the highest de-
gree that property expressed best by the French term " eclat."
It is rather difficult to see why the blue tint should be more
prominent after the metal has been worked, yet I think two
reasons will explain this phenomenon ; first, aluminium is not a
hard metal, and on polishing or burnishing, particles of dirt or
foreign substances are driven into the pores of the metal,,
thereby altering its color slightly ; second, any metal looks
whiter when its surface is slightly rough than when highly
polished, in the latter case it being as much the reflected color
of the general surroundings as the color of the metal itself
which is seen. I have never seen any highly polished white
metal which did not look bluish, especially when reflecting out-
door light. I think this explains why opera-glasses, rings,
jewelry, etc., generally look bluer than the bar or ingot-metal
from which they are made.
Aluminium takes a very beautiful mat, which keeps almost
indefinitely in the air, the surface thus slightly roughened ap-
pearing much whiter than the original polished surface. Alu-
minium can be polished and burnished without much difficulty
if attention is given to a few particulars which it is necessary to
observe. (For methods of poHshing, etc., see Chapter XIII.)
Extremely thin films of aluminium are fine violet-blue by
transmitted light.
Fracture.
A cast ingot of purest aluminium has a slightly fibrous
structure, a section y^ inch thick bending twenty degrees or
PHYSICAL PROPERTIES OF ALUMINIUM. 6 1
SO from a straight line when sharply bent before showing cracks
at the outside of the turn. The fracture of such an ingot is
uneven, rough, and very close, often showing a curious semi-
fused appearance, as if it had been already exposed to heat and
the sharpest points melted down. However, only the purest
varieties show these peculiarities. Metal containing 96 to 97
per cent, of aluminium begins to show a crystalline structure,
breaks short, and with a tolerably level surface. Metal less
than 95 per cent, pure shows large shining crystal surfaces on
the fracture, the smaller crystals being on the outside of the
ingot where it has been cooled most quickly, while in the cen-
tre the crystalline surfaces may be as large as tV inch in
diameter. A specimen containing only 85 per cent, of alumin-
ium broke as short as a bar of antimonial lead, with a large
granular, crystalline surface.
Working the metal increases its fibrousness greatly, the sec-
tion of a square rolled bar of good metal looking very much
like that of a low-carbon steel.
Hardness.
The purest aluminium is distinctly softer than the commer-
cial ; estimated on the scale of hardness proposed by Mohs it
would be written as about 2.5, that is, a little harder than can
be scratched by the nail. It is not so soft as pure tin. The
presence of impurities, however, rapidly increases the hardness.
While 99 per cent, aluminium can be cut smoothly with the
knife and shavings turned up almost as with pure tin, yet 95
per cent, metal can hardly be cut at all ; the shavings break off
short, and a fine grating is felt through the blade.
Aluminium becomes surface hardened by cold working.
Castings of aluminium drop-forged cold, in dies, are made
sensibly harder and thus adapted for standing more wear.
Cold drawing or rolling gives to it nearly the hardness of brass.
In a drop test to investigate this quality made in the Pittsburgh
Testing Laboratory, the following comparative results were
reached :
62 ALUMINIUM.
Hardness.
Aluminium, rolled 62
Aluminium, cast 47
Brass, rolled 86
Brass, cast 71
Copper 100
Experience in testing various specimens of commercial alu-
minium with the knife will, I am sure, enable a person to be-
come quite skillful in determining the purity and in separating
different grades from each other. Taking this test in connec-
tion with the breaking and surface of fracture, it appears to me
that these indications are as significant and can be made of as
much use as the corresponding tests for iron, steel, and other
metals. Mr. Joseph Richards, the author's father, having had
many years' experience in testing lead, tin, zinc, and similar
metals, in which the knife-blade has been put to good service,
has been able with very little practice to arrange a number of
specimens of aluminium correctly according to their purity sim-
ply by noting carefully the way they cut and the color of the
cut surface. These tests will in the future, I am sure, be of
great use to those handling aluminium on a large scale, es--
pecially in the works where it is produced.
Specific Gravity.
Mallet: The specific gravity of absolutely pure aluminium-
was carefully determined at 4° C, and the mean of three
closely agreeing observations gave 2.583.
Commercial aluminium is almost always heavier than this,
but the increase is not in direct proportion to the amount of
impurities present. There are two reasons why this last state-
ment is correct; first, we cannot say what expansion or con-
traction may take place in forming the alloy; second, while-
most of the impurities which occur are much heavier than alu-
minium, yet silicon, the most frequent of all, has a specific
gravity of only 2.34 (Deville's determination), and therefore
acts in the opposite direction to the other impurities, though.
PHYSICAL PROPERTIES OF ALUMINIUM. 63
not to SO great an extent. The following analyses and specific
gravities may give some information on this point: —
Analysis.
Specific Gravity.
Aluminium.
Silicon.
Iron.
Observed.
Calculated.
97.60
0.60
1.80
2-73S
2.61 (2.64)
95-93
2.01
2.06
2.800
2.61 (2.69)
94.16
4-36
1.48
2.754
2.59 (2.74)
78.-
16.—
4-—
2.85
2.66
It is seen in each case that the calculated specific gravity is.
much less than the observed, which would show contraction in
volume by alloying. Indeed, this is a prominent characteristic
of aluminium alloys, aluminium often taking up several per
cent, of its weight of another metal without its volume being
increased, the particles of the other metal seeming to pass be-
tween those of the aluminium ; thus probably accounting for
the extraordinary strength and closeness of many of the alumin-
ium alloys. This subject is treated more at length in the chap-
ter on alloys. We can see the large contraction taking place
by inspecting the numbers in parentheses under the heading
"Calculated." These are computed on the supposition that
the volume of the impure aluminium is equal to that of the
pure aluminium entering into it. As these numbers are also-
less than the observed specific gravities, the extraordinary fact
is shown that aluminium can absorb several per cent, of iron
and silicon and yet will decrease in volume in doing so.
The remarks thus far made are based on the gravity of cast
metal. Aluminium increases in density by being worked : De-
ville states that metal with a specific gravity of 2.56 had this
increased to 2.67 by rolling, which, he says, may explain the
diflerences existing in its properties after being annealed or
worked. He remarked further that heating this rolled metal to
100°, and cooling quickly, changed its specific gravity very little,
lowering it to 2.65. I have observed that on heating a piece of
aluminium almost to its fusing point and suddenly chiUing it in
water, its specific gravity was lowered from 2.73 to 2.69.
64 ALUMINIUM.
Experiments made by Prof. J. W. Langley with aluminium
98.52 per cent, pure, the rest being mostly silicon, gave its
specific gravity as follows :
Sample sawn from centre of a cast ingot 2.587
Same, annealed 2.692
Rolled into sheet 0.0625 inch thick 2.710
Stamped into medals 2.725
The low specific gravity of aluminium, when compared with
that of the other metals, is (in the words of a recent lecturer)
" the physical property on which our hopes of the future use-
fulness of aluminium chiefly rest." The following table will
facilitate this comparison :
Specific Gravity.
Alumin- Founds in a Kilos in .1
Water = I. ium =: i. cubic foot. cubic meter.
Platinum 21.5 8.3 1344 21,500
Gold 19.3 7.4 1206 19,300
Lead 11.4 4.6 712 11,400
Silver 10.5 4.0 656 10,500
Copper 8.9 3.5 557 8,900
Iron and steel 7.8 2.8 487 7,800
Tin 7.3 2.7 456 7,300
Zinc 7.1 2.7 444 7,100
Aluminium 2.6 i.o 163 2,600
In comparing the price of aluminium with that of a metal
which it might replace, for purposes where the bulk of the arti-
cle is fixed, it is of first importance to take this low specific
gravity into account. When we come to consider closely, we
find that almost every article of use or ornament is wanted of a
fixed size, and therefore the real basis of comparison of prices is
that of a fixed volume of the metal rather than a fixed weight.
To facilitate this comparison, I give below the actual market
prices of one pound weight of the common metals, with the
prices of equal volumes:
PHYSICAL PROPERTIES OF ALUMINIUM. 65
Value of Relative cost Value of Relative cost
I pound, of equal weights, i cubic foot, of equal volumes.
Silver jSio.oo 2850 ;J656o.oo 1 1430
Nickel 0.50 140 279.00 468
Aluminium 0.35 100 S7-S0 10°
German silver 0.30 85 167,00 290
Tin 0.15 43 68.50 120
Bronze 0.15 43 79.00 137
Brass 0.12 34 61.75 107
Copper o.io 28 55.75 97
Lead 0.04 11 28.50 50
Zinc 0.04 II 17-75 3'
Steel 0.02 6 9.75 17
Cast Iron o.oi 3 5.00 8
It is therefore evident, that for almost all uses to which
aluminium is applicable, there are only five of the common
metals which are cheaper, viz., copper, lead, zinc, steel and cast-
iron. When it is further remembered that the cost of the metal
alone usually forms only a small part of the value of the finished
article, it can be further asserted that there should be only a
trifling diflference between the cost of an article made in alu-
minium and one of tin, bronze, brass or copper. The sole
reason why aluminium articles are not sold more cheaply at
present, lies in the fact that they are not made and sold in such
large quantities ; the increase of the aluminium industry will
therefore ensure lower prices for aluminium goods.
Fusibility.
Deville : Aluminium melts at a temperature higher than that
of zinc, lower than that of silver, but approaching nearer to that
of zinc than silver. It is, therefore, quite a fusible metal.
Mallet : It seems that pure aluminium is a Httle less fusible
than the commercial metal.
Pictet determined the melting point to be 600°, Heeren about
700°, while Van der Weyde placed it as high as 850°. On a
sample containing 0.5 per cent, of iron, Carnelly determined
the melting point at 700° ; with 5 per cent, of iron it did not
fuse completely until 730°. The discordance between these
various experimenters lies chiefly in the errors of the pyro-
S
66 ALUMINIUM.
meters used. Since the perfection of the electric pyrometer by
Le ChateHer, the melting point of the purest aluminium has
been repeatedly observed as very close to 625°. This figure
is probably correct within 5°.
A very small admixture of iron and silicon lowers the melt-
ing point. Le Chatelier found with a metal containing 1.50
per cent, silicon and 0.75 per cent, iron, the melting point
619°- A larger quantity of either of these elements quickly
operates in the other direction, and prevents fluid fusion until
a temperature above 625° is reached.
Spring has determined that aluminium powder flows to a
solid mass at a pressure of 38 tons per square inch, at ordinary
temperatures.
Volatilization.
Deville : Aluminium is absolutely fixed, and loses no part of
its weight when it is violently heated in a forge fire in a carbon
crucible.
This statement was made in 1859, and can still be accepted
as true as far as ordinary furnace temperatures are concerned.
But, with the use of the electric furnace, temperatures have
been attained at which aluminium does sensibly volatilize. In
Cowles Bros, electric furnace it is stated that the aluminium is
almost all produced as vapor and as such is absorbed by the
copper or iron present ; when these are not present it is found
condensed in the cooler upper part of the furnace. A similar
experience has been met in other electric furnace processes, so
that the volatilization of aluminium at these extreme tempera-
tures may be accepted as a fact.
Aluminium vapor has been recently produced in an electric
furnace in large enough amounts to determine that it is of a
green-blue color.
Odor.
The purest aluminium has no perceptible odor, but metal
containing i per cent, or more of silicon exhales the odor of
silicon hydride, exactly the same odor as proceeds from cast
PHYSICAL PROPERTIES OF ALUMINIUM. 6^
iron. Second quality commercial aluminium gives this smell
quite strongly, but in the present first quality metal it is difficult
to detect it except by smelling immediately after a brisk
rubbing.
Taste.
The same remark may be made regarding taste as of the
odor. The purest metal has no taste ; the impure tastes like
iron, but not so strongly.
Magnetism.
Deville, as also Poggendorff and Reiss, state that aluminium"
is very feebly magnetic. It must be remembered, however, that
they tested metal made by the sodium process, which almost
invariably contained iron.
Prof. Frank Very, of the Allegheny Observatory, Allegheny,
Pa., finds aluminium with only a trace of iron to be absolutely
non-magnetic. With 0.05 per cent, of iron, none could be ob-
served. An ingot containing 1.5 per cent, iron showed faint
polarity, while with 2 per cent, the polarity was very decidedly
observed.
Since the present first quality commercial aluminium contains
less than 0.2 per cent, of iron, and frequently only 0.05 per
cent., we may observe that this is less than is usually found in
commercial brass, bronze or german-silver, and for this reason,
as well as its other valuable properties, aluminium answers very
well for compass boxes or cases, or parts of electrical instru-
ments where non-magnetic properties are desired.
Sonorousness.
Deville: "A very curious property, which aluminium shows
the more the purer it is, is its excessive sonorousness, so that
a bar of it suspended by a fine wire and struck sounds like a
crystal bell. M. Lissajous, who with me observed this prop-
erty, has taken advantage of it to construct tuning forks of
aluminium, which vibrate very well. I also tried to cast a bell,
which has been sent to the Royal Institution at London at the
-68 ALUMINIUM.
request of my friend Rev. J. Barlow, vice-president and secre-
tary of the institution. This bell, cast on a model not well
adapted to the qualities of the metal, gives a sharp sound of
considerable intensity, but which is not prolonged, as if the
clapper or support hindered the sound, which, thus hindered,
becomes far from agreeable. The sound produced by the in-
gots is, on the contrary, very pure and prolonged. In the ex-
periments made in Mr. Faraday's laboratory, this celebrated
physicist has remarked that the sound produced by an ingot of
aluminium is not simple. One can distinguish, by turning the
vibrating ingot, two sounds very near together and succeeding
each other rapidly, according as one or the other face of the
ingot faces the observer."
The bell referred to above was 20 kilos in weight and 50
centimetres in diameter, but as Deville admits, its sound was
not pleasing, and a contemporary writer, evidently not very
enthusiastic in sounding the praises of aluminium, said that
" while the bell was highly sonorous, yet it gave a sound like
a cracked pot."
I have not heard that any large bell has since been cast, but
it is certain that the metal in bars has a highly musical ring.
Faraday's observation has also been verified, for a recent lec-
turer suspended by one end a bar 6 feet long 31^ inches wide,
and I y^ inches thick, and on striking it a prolonged vibration
ensued, two notes being recognized, A sharp and D sharp, the
latter more subdued.
Within the last few years aluminium has been extensively
employed for sounding boards in public hails, the sounding
boards of pianos, and even for the construction of horns and
violins. The sounding board in the Lyceum Hall, New York
city, is an example. The particular advantage is, its not being
affected by a moist atmosphere. Dr. Alfred Springer, of Cin-
cinnati, in speaking of its use for sounding boards says,* " It
.differs from all other metals in the absence of the comparatively
* Trans. A. A. Adv. Science, 1891, vol. 40, p. 182.
PHYSICAL PROPERTIES OF ALUMINIUM. 69
continuous and uniform higher partial tones, which give in
other metals the tone-color called " metallic," and further, that
it also possesses an elasticity capable of sympathetic vibration
uniformly through a wide range of tone-pitch, which renders it
in this respect superior to wood."
Dufour has measured the velocity of sound in aluminium at
4950 metres per second, almost the same figure as for steel.
Crystalline Form.
Deville : " Aluminium often presents a crystalline appearance
when it has been cooled slowly. When it is not pure, the little
crystals which form are needles, and cross each other in all
directions. When it is almost pure it still crystallizes by fusion,
but with difficulty, and one may observe on the surface of the
ingots hexagons which appear regularly" parallel along lines
which centre in the middle of the polygon. It is an error to
conclude from this observation that the metal crystallizes in the
rhombohedral system. It is evident that a crystal of the regu-
lar system may present a hexagonal section; while on the
other hand, in preparing aluminium by the battery at a low
temperature, I have observed complete octahedrons which were
impossible of measurement, it is true, but their angles appeared
equal."
By slowly cooling a large body of melted aluminium and
pouring out the fluid interior, distinct octahedrons may be
observed.
Elasticity.
Cast aluminium is not very elastic; it may be likened in this
respect to cast silver. When worked, however, it becomes
more rigid and elastic.
Mallet remarked that absolutely pure aluminium seemed to
be less hardened by hammering than ordinary commercial
metal.
Cast aluminium stiffens up very quickly in rolling or drawing,
and the strains set up in the metal can be removed by an
yo ALUMINIUM.
annealing, which consists in heating the metal to an incipient
red heat and then either allowing to cool slowly, or leaving a
few minutes at that heat and then cooling quickly by plunging
into water. Metal thus treated becomes very soft and pliable,
hardly any more elastic than lead, and will stand considerable
working before it again becomes stiff and elastic. The presence
of 2 to 5 per cent, of copper, nickel, silver, German-silver or
titanium increases very greatly the elasticity of aluminium
without increasing noticeably its specific gravity or impairing
its malleability.
Tensile and Compressive Strength.
W. H. Barlow* was the first to carefully test the tensile
strength of aluminium. He used a rolled bar one-quarter
inch square. With -a test piece two inches long, the tensile
strength was found to be 26,800 pounds per square inch, with
elongation before breaking of 2.5 per cent.
Kamarschf tested aluminium wire, and obtained an average
of 12.5 kilos per square millimetre, equal to nearly 18,000
pounds per square inch. This wire must have been annealed,
while the bar tested by Barlow was worked stiff before testing.
Mr. Spilsbury, of the Trenton Iron Co., obtained with alu-
minium wire of one-sixteenth inch diameter a tensile strength
of 62,300 pounds per square inch, the wire having been drawn
with one annealing from a wire-rod one-sixth inch in diameter.
The same wire made 47 bends at a right angle before breaking.
A most valuable series of mechanical tests of aluminium
have been made by the Pittsburgh Reduction Company, and
are copied as follows| :
* Rpt. British Assoc. Adv. Science, 1882, p. 668.
fDingler, Vol. 172, p. 55.
J Transactions Am. Inst. Mining Engineers. Vol. XVIII., p. 528 (1890).
PHYSICAL PROPERTIES OF ALUMINIUM.
Tensile Tests.
n
No. I quality commercial metal, averaging
over 98 per cent. pure.
Ordinary castings of over \ inch sectional
area, as cast ....
Same, annealed
Same castings, hardened by drop forging cold
Rolled bars, left hard
Same, annealed
Hammered bars, left hard
Same, annealed
"Wire i to J inch diameter, as drawn
Same, annealed
Wire y\ to -^^ inch diameter, as drawn
Wire ^ to ^ J ^ inch diameter, as drawn
Same, annealed
Plates to \ inch thick, as rolled
Same, annealed
Sheets \ to -^-^ inch thick, as rolled
Same, annealed
Sheets ^V '° ttss '^^'^ 'C!\\<^, as rolled
Same, annealed
•a 3 §
6,132
6,600
10,000
16,000
13.870
14,630
14,000
12,000
10,870
32,000
26,000
21,000
9.300
8,500
12,500
10,700
13.500
11,000
c
»H 4) u
■a p-.s
rt ^ rt
15,640
17,100
24,000
32,500
25,000
24,120
22,000
24,500
22,830
54,000
49,000
33,000
22,740
17.740
25,000
21,070
27,500
23,000
•a .
& O
a a
4) j-j •
"S "> So
8.66
15.00
18.00
42.00
49.11
3S-H
43.00
58.46
65-57
68.00
54.00
62.00
12.40
13-73
35-50
39.00
40.00
43-50
3,000
3,500
3.000
6,000
6,000
5.500
5,500
4,500
4,500
12,000
10,000
7,000
4,000
4,000
4.500
4,500
4,500
4,500
72
ALUMINIUM.
Compressive Tests.
Same metal is in above tensile
tests, about 98 per cent. pure.
Ordinary casting, as cast
Same, annealed
Same, hardened by drop forging.
Rolled bars, left hard
Same, annealed
Hammered bars, left hard
Same, annealed
Metal containing 4.5 per cent,
silicon and 1.5 per cent, iron,
casting, unannealed
Metal containing 1.14 per cent,
silicon and 0.05 per cent, iron,
castings, unannealed
Same, larger test-piece
.d
DA .
•S.J-
g^^
•= 0. c
"»-S a
e »■"
a-"
0, a <u
imat
n po
quar
^^ .« (fl
S
P
3.565
12,730
2,037
10,185
4,583
15,275
2,263
9,054
2,043
6,809
5,659
11,32c
5,094
11,320
4,800
15-275
4,583
12,730
5,094
11,320
'u a
Height X diam.
I in. X 0.5 in.
I in. X 0.5 in.
I in. X 0.5 in.
1.5 in. X 0.75 in.
1.5 in. X 0.75 in.
m. XI.5 m.
in. X 1.5 in.
I m. X0.5 m.
I in.xo.5 in.
3 in. X 1.5 in.
Height X diam.
0.985 X 0.503
0.975 * 0.506
0.965 X 0.508
1.459x0.760
1.468x0.756
2.91 X 1.520
2.91 X 1.519
0.965 X 0.508
0.975 X 0-507
2.92 X 1.519
Transverse Tests.
Metal containing 98.52 per cent, aluminium,
1. 14 per cent, silicon, and 0.05 per cent. iron.
Test-piece one inch square, supported on knife
edges 24 inches apart, loaded in the centre . . .
Same metal, test-piece a 1.5 inch diameter rolled
bar, on knife-edges 12 inches apart, loaded in
the centre
Load,
Deflection,
Permanent
pounds.
inches.
set, inches.
50
/l
A
100
S^
—
150
w
W
175
11
—
200
II
\%
225
H
—
250
III
m
275
If?
m
300
2H
2A
Not
ruptured.
1,000
A
0
1,500
A
A
2,000
M
A
2,500
H
—
2,800
\\
—
Broke.
PHYSICAL PROPERTIES OF ALUMINIUM.
7Z
From the various tests above enumerated, Messrs. Hunt,.
Langley and Hall draw the following general conclusions :
The average strength of commercial aluminium of the follow
ing average composition :
Aluminium 97. to 99. per cent.
Graphitic silicon o.i to i.o "
Combined " 0.9 to 2.8 "
Iron 0.04 to 0.2 "
is as follows :
Elastic limit in tension.
i- Castings.
Sheet . . .
Wire....
I Bars
Pounds per square inch.
6,500
12,000
16,000-30,000 (according to fineness)'
14,000
Ultimate strength in ten-
sion
15.000
24,000
30,000-65,000 (according to fineness)
28,000
Percentage of reduction
Castings .
Sheet...
r
iction j
of area, in tension .... ] Wire
L Bars.
15 per cent..
35 "
60 "
40 "
Pounds.
Elastic limit in compression in cylinders with length twice the diameter 3,50o
Ultimate strength ■ 12,000
Modulus of elasticity, castings 1 1,000,000
" " cold-drawn wire 19,000,000
" " sheets and bars 13,000,000
Professor Le Chatelier * has shown that the tensile strength
of annealed aluminium wire varies with the temperature as
follows :
Kilos per sq. millimetre. Pounds per sq. inch.
At 0° C. 1 8 26,000
150° 13 18,500
250° 7 1 0,000
300° 5 7^000
40o<^ 2 3,000
* Lejeal's Aluminium.
74 ALUMINIUM.
Minet found the following properties for aluminium strongly
worked and annealed :
Tensile strength. Elongation.
Kilos per sq. mm. Pounds per sq. in. Per cent.
After working 23.5 33iOOO 3
After being annealed I hour at 400° 15.1 21,500 17
He concludes from these results that, by careful annealing at
proportionate temperatures and for proportionate times, any
given strength between these limits may be obtained, or any
■desired elasticity from 3 to 17 per cent.
The results obtained for the tensile strength of aluminium
show, in general, that it is greatly influenced by the amount of
work done on the metal ; that while the pure, unworked metal
is by no means rigid, but elongates 10 to 20 per cent, before
breaking, as it is worked it becomes stififer and more elastic, its
strength may be nearly doubled, but it becomes at the same
time more brittle, as is shown by its elongation falling to 3 or 5
per cent. After working, increased elongation can be given to
it by annealing, but at the expense of ultimate strength. The
annealed material, however, would be a safer rhaterial to use in
any place where sudden shocks had to be sustained, if worked
within its elastic limit.
Taking the tensile strength of aluminium in relation to its
weight, it shows a very high mechanical value ; in fact, the only
material which can compare with it in tensile strength, weight
for weight, is the finest steel or aluminium bronze. A com-
parison on this basis is frequently made, in order to determine
the material which gives the greatest strength for a given
weight, or, rather, a given strength with the least weight. For
instance, we might make the comparison by calculating the
weight of rods of the different metals which would support a
certain maximum strain before breaking, and from these num-
bers derive a table of the relative weights of the metals to give
a certain strength :
PHYSICAL PROPERTIES OF ALUMINIUM. 75
Tensile strength, Relative strength Relative strength
Rolled Bars or Large Wire. pounds per sq. in. for same section, for same weight.
Aluminium 30,000 100 100
Cast steel 100,000 333 135
Soft steel 75,000 250 87
Wrought iron S5,oco 183 63
Aluminium bronze ....... 100,000 333 118
" brass 60,000 200 70
Gun bronze 35,000 117 37
Red brass 45,000 150 47
Copper 33,000 1 10 33
It results from this comparison that only steel of the highest
quality and the best aluminium bronze will give a greater
strength for a given weight than aluminium. Steel, however,
is subject to rust, whereas aluminium is not ; aluminium bronze
itself is a metal requiring considerable skill in working it to
always obtain the highest results ; these two are the only com-
petitors which aluminium has for constructions where great
strength combined with lightness is the first requirement, and
expense is a secondary consideration.
Malleability.
Aluminium stands high in the list of malleable metals. It
can be forged or rolled as easily as gold or silver, and can be
beaten out into leaf.
Mallet found that absolutely pure aluminium is decidedly
more malleable than the commercial metal, and is less hardened
by working. Experience in rolling it on a large scale has since
shown that the more impurity in the metal the harder it is to
work, and the quicker it will become hard and need annealing.
Some impurities, however, are more detrimental than others.
One per cent, of iron renders the metal stronger and harder to
roll, but more than this amount renders it less and less malle-
able, until with 6 per. cent, it is crystalline and brittle. On the
other hand, silicon may occur alone up to nearly 10 per cent,
without rendering the metal unfit for rolling.
Aluminium is most malleable between 100° and 150° C, and
can be worked some time at that temperature before becoming
76 ALUMINIUM.
hard. If rolled or worked cold, it needs more frequent anneal-
ing. While annealed aluminium is one of the softest and most
pliable metals, yet by cold working it can be given the stiffness
and temper of hard brass. The best commercial metal is
regularly rolled into sheets one-thousandth of an inch in thick-
ness, which sheets are sold for beating purposes, and it has
been rolled to one-half that thickness.
Metal for beating into leaf must be of the finest quality, i. e.,
over 99 per cent. pure. Rousseau, of Paris, was the first to
make aluminium leaf, and it was afterwards made for several
years by C. Falk & Co., of Vienna. At present, Mr. Kemp, of
New York, manufactures it on a large scale. The beating is a
little harder than is required for gold and silver, but by starting
with the purest aluminium equally thin leaf can be obtained.
A specimen of commercial aluminium leaf examined by the
writer had a thickness of 0.000638 millimetre, or one forty-
thousandth of an inch, which compares favorably with ordinary-
silver leaf. This leaf was opaque, but the thinnest attainable
leaf is a fine blue by transmitted light. No other useful metals
except gold and silver will show such malleability. This leaf is
now in regular use with gilders and decorators, and has en-
tirely superseded silver leaf because of its cheapness and non-
tarnishing qualities. The leaf is also rubbed into powder, and
in that state used as a metallic dust in printing and decorating.
Ductility.
Aluminium can be drawn into very fine wire. Even as early
as 1855, M. Vangeois made very fine wires with metal far from
being pure, and used them for making aluminium passementerie.
The metal quickly hardens at the drawing plate, and must be
frequently annealed. The larger sizes of wire can be drawn
warm, and then require less frequent annealing. The heated
gases from the chimney of an Argand burner will anneal the
very fine wires if they are simply passed across it. Wire as
fine as o.i millimetre (one two-hundred-and-fiftieth of an inch)
can be made without much trouble, while wire one-seventieth
PHYSICAL PROPERTIES OF ALUMINIUM. "JJ
of an inch in diameter is regularly kept in stock by the alu-
minium dealers.
Gold, silver, platinum, iron and copper are probably the only
metals more ductile than aluminium.
Expansion by Heat.
Fizeau determined that aluminium expands 0.00222 of its
length in passing from the freezing point to the boiling point,
or 0.0000222 of its length for a rise of 1° Centigrade, equal to
O.OOOOI129 per 1° Fahrenheit.
Prof. J. W. Langley examined metal 98.5 per cent, pure, the
rest being mostly silicon, and obtained for the expansion for
1° C. 0.0000206, which would be o.ooooi 15 for 1° F.
A bar of aluminium i foot long at 0° C. would, according to
Fizeau, be 1.00222 feet long at 100°, while a cubic foot of
aluminium at 0° would occupy 1.00666 cubic feet at 100° C,
since the rate of cubical increase is three times that of linear
expansion. This rate of expansion is close to that of tin,
among the common metals.
Specific Heat.*
The best experimenters have given various values for the
specific heat of aluminium, but it is very evident to the writer
that the differences are mainly due to differences in the purity
of the metal used. Professor Mallet used absolutely pure alu-
minium (purified for atomic weight determination), and the
writer used metal which analyzed 99.93 per cent, pure, and con-
tained but a trace of iron, while the other experimenters used
■ordinary commercial metal made by the sodium process and
■containing considerable quantities of iron.
Regnault, in 1855, used metal containing only 88.35 percent,
of aluminium. His figure of 0.2056, between 25° and 97°, is,
therefore, only approximate.
* For further details, see papers on this subject by the author in Journal of the
franklin Institute, April, 1892, and July, 1893.
78 ALUMINIUM.
In 1856, Regnault obtained metal 97 per cent, pure, with
which he obtained O.2122 (14° to 97°).
Kopp, in 1863, used Parisian aluminium containing two per
cent, of iron, and obtained a value varying between O.1970 and
0.2070 (20° to 52°). His results are unreliable.
In 1882, Mallet found the mean specific heat from 0° to 100°,
using absolutely pure aluminium, 0.2253.
Tomlinson * used commercial aluminium in wire, and gives
the following formula for the mean specific heat, from any
given temperature to 0° C. :
Sm = 0.2070 4" O.OOOI 151.
This would give from 0° to 100°, 0.2185.
Naccari f used commercial metal, and gives the following for-
mula, which expresses his results up to 300° C. :
Sm = 0.2116 + 0.0000475 *•
This would give from 0° to 100°, 0.2 164.
Le VerrierJ stated that he found, using best commercial
metal, the specific heat between 0° and 300° to be invariable,
and = 0.22 ; between 300° and 530° also constant, and = 0.30;
between 530° and 560° an absorption of heat, rendered latent,
of about 10 calories; between 540° and 600° the specific heat
again constant, and = 0.46. For the total quantities of heat
in the metal, at various temperatures, he gives :
o'' to 300° Q = 0.22 t.
300° to 530° Q = 65 + 0.30 (t— 300).
540° to 600° Q = 139 -\- 0.46 (t — 530).
About 600° Q = 170.
Before fusion at 620° Q = 200.
These determinations would give the mean specific heat
from 0° to 100°, 0.2200. No other investigator, however, has
noticed the sudden jumps noted by Le Verrier, which, if true,
*Proc. Royal Society, 1885, p. 494.
t Trans. Accademia di Torino, Dec, 1887.
I Comptes Rendus, 1892, Vol. 114, p. 907.
PHYSICAL PROPERTIES OF ALUMINIUM. 79
are indeed very singular. Experiments by Pionchon and the
writer, about to be described, gave no indications of such criti-
cal points.
Pionchon* states that he used very pure aluminium, and ob-
tained the following formulae :
291-86 t
0° to 580° Q = 0.393 t- giy.8 4- 1
625° to 800° Q = 0.308 t— 46.9.
(Molten.)
This would give the specific heat at 0°, = 0.2010; the
mean specific heat 0° to 100° = 0.2 130; heat in solid alu-
minium at its melting-point, 160.5 calories; heat in molten
aluminium at the setting-point, 239.4 calories ; specific heat of
molten aluminium constant, and = 0.308. The latent heat of
fusion would be 239.4 — 160.5 = 7^-9 calories.
The writer, using aluminium which analyzed 99.93 per cent,
pure, with only a trace of iron and 0.07 per cent, silicon, ob-
tained the following formulae for solid aluminium up to 600° :
Mean specific heat to o°- Sm = 0.2220 -|- 0.00005 t.
True specific heat at t°- S = 0.2220 -\- o.ocoi t.
Total heat to o°- Q = 0.2220 1 -|- 0.00005 t'.
These formulae give for the specific heat at 0° =0.2220;
the mean specific heat 0° to 100° = 0.2270; the heat in solid
aluminium at the melting-point, 158.3 calories; specific heat at
the melting-point, 0.285.
Regarding these figures, it will be observed that the mean
value 0° to 100° is less than i per cent, different from Mallet's
result, and therefore these values may be accepted as the true
value of the mean specific heat between those temperatures.
Regarding the value for the heat contained at the melting-point,
it is only a fraction over i per cent, removed from that given
by Pionchon's formula. It must not be forgotten, however,
that aluminium begins to soften at about 600°, and some of its
latent heat of fusion is absorbed before the true melting-point,
*Comptes Rendus, 1892, Vol. 115, p. 163.
So ALUMINIUM.
625°, is reached, as observed by both Pionchon and Le Verrier.
The numbers given by the formulae are the theoretical amounts
of heat which the metal would contain at 625°, provided that
none of the latent heat of fusion had been previously absorbed.
To determine the amount of heat in the molten metal at its
setting point the writer made several determinations by pour-
ing the metal into water, just as it was setting. The result
showed that the purity of the metal had a great effect on the
amount of heat thus given up.
Aluminium 96.9 per cent, pure gave up 229.0 calories.
99-9 " " " 254-0 "
99-93 " " " 258.3 "
It is seen that a small amount of impurity makes a large
difference, which is really caused by the impurity lowering the
melting point of the metal. Since the metal used by Pionchon
was not over 99.7 per cent, pure, we have a partial explanation
of why he obtained only 239.4 calories in the molten metal.
The figure deduced by the writer for the latent heat of fusion
of aluminium is therefore 258.3 — 158.3=100 calories.
The value of the specific heat of aluminium determined by
Mallet and the writer agrees best with Dulong and Petit's law,
as is seen by the following comparison of the actual and atomic
specific heats for the interval 0° to 100° :
Experimenter. Specific Heat x Atomic Weight= Atomic Heat.
Regnault 0.2122 x 27.0 = 5.73
Kopp 0.2020
Tomlinson 0.2185
Naccari 0.2164
Le Verrier 0.2200
Pionchon 0.21 30
Mallet 0.2253
Richards . 0.2270
S-45
5-90
5-88
5-94
5-75
6.08
6.13
Since for all the common metals the product of the atomic
weight by the specific heat for this range of temperature is in-
variably above 6.0, and averages 6.2, the conclusion is plain
that the last two figures given above must be the correct ones.
PHYSICAL PROPERTIES OF ALUMINIUM. 8 1
The high value of the specific heat of aluminium compared
with other metals, and particularly its large latent heat of
fusion, cause the metal to melt very slowly even in a very hot
fire. As seen above, over 258 calories have to be absorbed
in order to raise it to the melting point and melt it. It com-
pares with other metals as follows :
Aluminium 25^-3 calories.
Cast iron 250.0 "
Copper 162.0 "
Platinum 102.4 "
Silver 85.0
Gold 58.0 "
We can therefore deduce the interesting fact, which is amply
confirmed by observation, that having a furnace hot enough to
melt cast iron, we would find that a given weight of gold, silver
or copper would melt before the same weight of aluminium,
and even the cast-iron would not be far from melting by the
time the aluminium fused.
Electric Conductivity.
Aluminium is a very good conductor of electricity. Metal
used for electrical purposes should be of the best quality, and as
free as possible from intermingled slag or blow-holes, which
impair greatly its conductivity.
Taking the electrical conductivity of absolutely pure silver or
copper as 100, we cite the following determinations :
Silver = 100. Copper = 100.
Mattheissen. Commercial aluminium 33-76
Benoit. Annealed wire 49-7°
Watts 5610
*Lorenz 49.1 at 0°.
■< 50.1 at 100°.
'■ Unnealed wire 54.8 at 14°.
" 53-7 at 76°.
Annealed " S7.4 at 14°.
" " SS-9 at 76°.
Weiler. Best commercial metal S4-20 54.3
tC. K. McGee. Metal used
98.52 per cent. pure.
* Wied. Annalen, | 2], xiii, 422, 582 (1881).
t Trans. Am. Inst. Mining Engineers, xviii, 528 (1890).
6
82 ALUMINIUM.
The later determinations of McGee and Weiler agree very
satisfactorily. Taking 54.8 as the relative resistance at ordinary
temperatures, a wire of aluminium o.i inch in diameter and lOO
feet long would have a resistance of 0.20235 ohms.
Professor Dewar has recently investigated the electrical re-
sistance of the metals at very low temperatures. He finds with
aluminium, as with other metals, that the resistance varies
directly as the absolute temperature. The following are his
results :
Relative Electrical Resistances.
Temperature, Pure Silver. Pure Copper. Aluminium.
C° .... .... 99 per cent. 97.5 per cent.
ig.i 1588 1682 2772 2869
i.o 2583 2683
—82 1704 1738
—197 .... .... 560 506
—219 .... .... .... 325
Thermal Conductivity.
Faraday stated that he had found by a very simple experi-
ment that aluminium conducted heat better than either silver
or copper.
L. Lorenz of Copenhagen, in the Jahresbericht der Chemie,
1881, p. 94, stated that he had found it inferior to both of these
metals, and later investigations have confirmed this.
Professor Carhart, of the University of Michigan, finds that
annealed aluminium is a slightly better heat conductor than
the unannealed.
The various results are as follows :
Silver = 100, Copper = loo.
L. Lorenz 47-72 at 0°.
L. Lorenz ; . 50.00 at 100°.
Calvert and Johnson 66.5
Prof. Carhart. Annealed Metal 38.87 52.8
Prof. Carhart. Unannealed Metal 37-96 51.6
Gold is the only other metal which conducts heat better than
aluminium.
CHAPTER IV.
CHEMICAL PROPERTIES OF ALUMINIUM.
We would here repeat the remark made with regard to the
physical properties, that the properties to be recorded are those
of the purest metal unless specifically stated otherwise. How-
ever, the high grade of commercial metal differs very little in
most of its chemical properties from the absolutely pure, so
that not many reservations are necessary in applying the fol-
lowing properties to good, commercial metal:
Atomic Weight.
The most accurate determination which we have is that of
Professor Mallet, who found 27.02. For all practical purposes,
and even in analyses, it may be conveniently considered as 27.
The chemical equivalent weight is one-third of this, or 9.
Action of Air.
Deville: "Air, wet or dry, has absolutely no action on alu-
minium. No observation which has come to my knowledge
is contrary to this assertion, which may easily be proved by
any one. I have known of beams of balances, weights, plaques,
polished leaf, reflectors, etc., of the metal exposed for months
to moist air and sulphur vapors and showing no traoe of alter-
ation. We know that aluminium may be melted in the air with
impunity, therefore air and also oxygen cannot sensibly afifect
it. It resisted oxidation in the air at the highest heat I could
produce in a cupel furnace, a heat much higher than that re-
quired for the assay of gold. This experiment is interesting,
especially when the metallic button is covered with a layer of
oxide which tarnishes it, the expansion of the metal causing
(83)
§4 ALUMINIUM.
small branches to shoot from its surface, which are very bril-
liant and do not lose their lustre in spite of the oxidizing at-
mosphere. M. Wohler has also observed this property on try-
ing to melt the metal with a blowpipe. M. Peligot has profited
by it to cupel aluminium. I have seen buttons of impure
metal cupelled with lead and become very malleable.
"With pure aluminium the resistance of the metal to direct
oxidation is so considerable that at the melting point of plati-
num it is hardly appreciably touched, and does not lose its
lustre. It is well known that the more oxidizable metals take
this property away from it. But silicon itself, which is much
less oxidizable, when alloyed with it makes it burn with great
brilliancy, because there is formed a silicate of aluminium."
While the above observations are in the main true, yet it is
now well known that objects made of commercial aluminium do
after a long exposure become coated with a very thin film, which
gives the surface a "dead" appearance. The coating is very
similar in appearance to that forming on zinc under the same
circumstances. The oxidation, however, does not continue, for
the film seems to be absolutely cdntinous and to protect the
metal underneath from further oxidation. This coating can best
be removed by very dilute acid (see Mourey's receipt, p. 6o),
after which the surface can be burnished to its former brilliancy.
The action of air and rain water together also slightly cor-
rodes commercial aluminium, the sheet metal particularly
showing after several months exposure small white spots of
alumina wherever there was a speck or " piqfire." In no case,
however, is this corrosion very strong or anything like as
serious as the rusting of iron or corrosion of brass, copper, etc.
It has also been found that at a high white-heat, especially
at the heat of an electric furnace, aluminium burns with a strong
light to alumina. It is quite probable that in this case it
volatizes first, and it is the vapor which burns. During the
operation of an electric furnace a white smoke formed of invisi-
ble particles of alumina is thus formed and evolved from the
furnace. Also, in melting aluminium, even the purest, it will
CHEMICAL PROPERTIES OF ALUMINIUM. 85
be found that the surface seems bound and the aluminium
restrained from flowing freely by a minute " sl^in " which may
probably be a mixture of oxide with metal, or perhaps of oxides
of foreign metals ; but, nevertheless, it is always present and is
therefore indicative of oxidation taking place. It seems to pro-
tect the metal beneath it perfectly, so that, once formed, it gets
no thicker by continued heating.
Wohler first discovered that when aluminium was in the ex-
tremely attenuated form of a leaf it would burn brightly in air,
and burn in oxygen with a brilliant bluish-light. It is also said
that thin foil will burn in oxygen, being heated by wrapping it
around a splinter of wood, and fine wire also burns like iron
wire, but the combustion is not continuous, because the wire
fuses too quickly. The alumina resulting is quite insoluble in
acids, and as hard as corundum.
The aluminium powder, produced by pulverizing aluminium
leaf, burns brilliantly when projected into a flame, and has dis-
placed, to a large extent, magnesium powder for making a flash
Hght, because it is cheaper, gives a more strongly actinic light,
and leaves no unpleasant smoke or fumes. For this purpose it
is not used pure, but mixed with various chemicals, for the
composition of which see the chapter on "Uses of Aluminium."
Action of Water.
Deville : " Water has no action on aluminium, either at ordi-
nary temperatures or at 100°, or at a red heat bordering on the
fusing point of the metal. I boiled a fine wire in water for half
an hour and it lost not a particle in weight. The same wire was
put in a glass-tube heated to redness by an alcohol lamp and
traversed by a current of steam, but after several hours it had
not lost its polish, and had the same weight. To obtain any
sensible action it is necessary to operate at the highest heat of
a reverberatory furnace — a white heat. Even then the oxida-
tion is so feeble that it develops only in spots, producing almost
inappreciable quantities of alumina. This slight alteration and
■the analogies of the metal allow us to admit that it decomposes
86 ALUMINIUM.
water, but very feebly. If, however, metal produced by M.
Rose's method is used, which is almost unavoidably contam-
inated with slag composed of chlorides of aluminium and
sodium, the former, in presence of water, plays the part of an
acid towards aluminium, disengaging hydrogen with the forma-
tion of a subchlorhydrate of alumina, whose composition is not
known, and which is soluble in water. When the metal thus
tarnishes in water one may be sure to find chlorine in the water
on testing it with nitrate of silver."
Aluminium leaf, however, will slowly decompose water at
ioo°. Hydrogen is slowly evolved, the leaf loses its brilliancy,
becomes discolored, and, after some hours, translucent. It is
eventually entirely converted into gelatinous hydrated alumina.
A. Ditte * explains the action of water on aluminium as fol-
lows : Water can only act on aluminium by producing hydro-
gen gas and alumina, both of which deposit on the metal and
cover it with a thin, protective coating. If the conditions are
such that this coating is removed, the action becomes manifest.
Boiling, for instance, removes the hydrogen, and if chloride,
sulphate or nitrate of aluminium be present in the solution to
remove the alumina, the action goes on, a basic salt being
formed, and continues until a sub-salt is formed which is diffi-
cultly soluble or insoluble, and covers the metal with a new,
impermeable coating. Traces of these acids in the boiling
water would lead to the same result.
Action of Hydrogen Sulphide and Sulphur.
Deville : " Sulphuretted hydrogen exercises no action on
aluminium, as may be proved by leaving the metal in an
aqueous solution of the gas. In these circumstances almost all
the metals, and especially silver, blacken with great rapidity.
Sulph-hydrate of ammonia may be evaporated on an alumin-
ium leaf, leaving on the metal only a deposit of sulphur, which
the least heat drives away.
* Ann. de Chimie et de Physique [6], Vol. 20, p. 404 (i8go).
CHEMICAL PROPERTIES OF ALUMINIUM. 8/
" Aluminium may be heated in a glass tube to a red heat in
vapor of sulphur without altering the metal. This resistance is
such that in melting together polysulphide of potassium and
some aluminium containing copper or iron, the latter are at-
tacked without the aluminium being sensibly affected. Un-
happily, this method of purification may not be employed
because of the protection which aluminium exercises over
foreign metals. Under the same circumstances gold and silver
dissolve up very rapidly. However, at a high temperature I
have observed that ,it combines directly with sulphur to give
aluminium sulphide. These properties varying so much with
the temperafure from one of the special characteristics of the
metal and its alloys."
Margottet states that hydrogen sulphide is without action on
aluminium, as also are the sulphides of iron, copper, or zinc.
Aluminium is said to decompose silver sulphide, AgjS, setting
the sulphur, however, at liberty, and alloying with the silver.
In regard to its indifference to the first mentioned sulphides,
this would give inferential evidence that the reverse operation,
i. e., the action of iron, copper, or zinc on aluminium sulphide,
would be possible, as will be seen later to be apparently
established by direct experiment. As to the action of sul-
phuretted hydrogen, the author has a different experience to
quote. On passing a stream of that gas into commercial alu-
minium melted at a red heat, little explosive puffs were heard,
accompanied by a yellow light, while the dross formed on the
surface, when cooled, evolved sulphuretted hydrogen briskly
when dropped into water, and gave every indication of contain-
ing aluminium sulphide. It could not have been silicon sul-
phide, for the metal contained as large a percentage of silicon
after treatment as before. Hydrogen sulphide is also absorbed
in large quantity by molten aluminium, and mostly evolved just
as the metal is about to set. Some of the gas is entangled in
the solidifying metal, forming and fiUing numerous cavities or
blow-holes.
88 aluminium.
Sulphuric Acid.
Deville : " Sulphuric acid, diluted in the proportion most
suitable for attacking the metals which decompose water, has
no action on aluminium ; and contact with a foreign metal does
not help, as with zinc, the solution of the metal, according to
M. de la Rive. This singular fact tends to remove aluminium
considerably from those metals. To establish it better, I left
for several months some globules weighing only a few milli-
grammes in contact with the weak acid, and they showed no
visible alteration ; however, the acid gave a faint precipitate
when neutralized with aqua ammonia."
It is a fact that dilute or concentrated sulphuric acid acts
very feebly on pure aluminium in the cold, but on being heated
they both attack it, disengaging sulphurous acid gas. Impure
metal is attacked more easily than pure metal, the presence of
silicon giving rise to the formation of silicon hydride, which
communicates to the hydrogen set free a tainted odor.
Ditte* describes the action of sulphuric acid as follows : A
2.5 per cent, solution acts very slowly at first, if cold, but after
several hours the air condensed on the aluminium is removed
and the metal is slowly dissolved, evolving hydrogen. The
bubbles of hydrogen, however, protect the surface from further
attack, but anything which breaks up or removes this gaseous
envelope hastens the action of the acid. Certain solutions of
metallic chlorides which aluminium reduces act in this way.
If, for instance, we add a few drops of platinic chloride to the
above acid, platinum is reduced on the aluminium, the surface
is roughened, causing the gas to escape quicker, and the action
is much more rapid. Traces of chloride of gold, mercury or
copper have the same effect. After some time, the action of
the acid is stopped by the formation of an insoluble basic salt,
having the formula 4AI2O3.3SO3.18H2O, which deposits on the
metal and protects it from further action. Even very dilute
sulphuric acid attacks aluminium if it is prevented from cover-
ing itself with the layer of gas, as by boiling.
♦Comptes Rendus, ex., pp. 583, 782 (1890).
B.
C.
D.
98.45
99.60
9947
1.30
0.30
0.40
0.25
O.IO
0.13
CHEMICAL PROPERTIES OF ALUMINIUM. 89
It appears to the writer that similar reasoning explains why
impure aluminium is attacked more rapidly. Aluminium being
electro-positive towards the impurities it contains, it follows
that when the aluminium is at all attacked by the acid the gas
will be disengaged on the particles of the impurity, and not on
the aluminium itself ; thus the pure aluminium will never get
the benefit of the gaseous protection, and the action proceeds
rapidly.
G. A. Le Roy* tested four specimens of commercial alu-
minium, whose analysis was as follows :
A.
Aluminium 98.28
Iron 1 .5o
Silicon o. 1 2
Specimens A and B were made by the sodium process at
Nanterre ; C and D by another process, not named. The metal
was in sheets and was cut to a definite size, cleaned in soda,
washed in alcohol, dried, weighed, and then put in the acid.
Afterwards they were withdrawn, washed with water, dipped in
alcohol, dried and weighed. The results are expressed as the
weight in grammes dissolved during twelve hours from a sur-
face of one square metre :
Specific
Quality of Acid. Gravity.
Pure 1.842
Commercial i .842
Pure 1. 711
Commercial 1. 711
Pure 1.580
Pure 1.263
Pure 1.842
Commercial i .842
From these tests Le Roy concludes that it is impracticable
to think of using aluminium for the different apparatus, such as
pans, pumps, tank linings, etc., used in the manufacture or
handling of sulphuric acid.
* Le Moniteur Industriel, Oct. 29, 1891.
Degrees
Temper-
Loss in grammes per square metre in t2 hours^
Baume.
ature.
A.
B.
C.
D.
66°
I5°-20°
18.40
18.90
16.40
14.5a
66°
21.00
21.30
17.50
16.40
60"^
24.50
25.00
22.00
20.00
70°
25.80
25.70
24.60
22.40
.S.S"
19.00
18.00
17.90
16.30
30°
4.60
.. ..
2.60
340
66°
150°
240
225
150
200
66°
150°
267
250
210
220
go ALUMINIUM.
While these tests show that the aluminium is certainly dis-
solved, yet they also prove that the action is very slow. If
these acids, for instance, were contained in an aluminium vessel
I millimetre in thickness (0.04 inch), we can easily calculate
from the above figures that the concentrated acid could rest in
it cold from 60 to 90 days before eating through ; the 30° acid,
which is yet strong, would take 290 to 560 days to get through
it; while even the hot concentrated acid would not get through
in less than 5 days' constant action. We can infer that cold,
dilute acid would probably take several years in producing the
same efTect.
Nitric Acid.
Deville : " Nitric acid, weak or concentrated, does not act on
aluminium at the ordinary temperature. In boiling acid, solu-
tion takes place, but with such slowness that I had to give up
this mode of dissolving the metal in my analyses. By cooling
the solution all action ceases. On account of this property,
M. Hulot has obtained good results on substituting aluminium
for platinum in the Grove battery."
Ditte* describes the action of nitric acid similarly to that
of sulphuric. Cold 3 per cent, acid acts very slowly, 6
per cent, quicker but slower than sulphuric acid of the
same strength. When the plate becomes rough or mat by
the action, the gas escapes more freely from the surface
and the attack is more rapid. The gas evolved contains
no hydrogen, but is mostly nitrous-oxide, similarly to the
action on zinc, with a little ammonia gas. The reaction does
not stop with the formation of the neutral nitrate, but this is
acted on by the aluminium, forming a white, granular precipi-
tate of a basic salt having the formula : 6AI2O3.3N2O5.30H2O.
While cold acid thus attacks the metal very slowly, the hot
concentrated acid at 100° attacks it violently.
The amount of the action of cold nitric acid has been mea-
sured by Le Roy, Lunge, and the writer, as follows :
* Vide, p. 88.
CHEMICAL PROPERTIES OF ALUMINIUM.
91
Le Roy, pure, concentrated i5"-20°
" commercial, concentrated ! "
" " 52 per cent ! "
Lunge, pure concentrated.
" " 65 per cent. . .
" " 32 per cent. . .
Richards, pure, concentrated.
25"
B *
6 5!"
cJ rt fi
t, jj -rH
^ t/> i^ u
31-50
37-35
30.00
0.38
4.00
10.27
96.00
The figure last given includes the loss sustained in polishing
the metal to its original appearance before immersion. It re-
sults from these tests that a sheet of aluminium one millimetre
thick, if left standing in concentrated nitric acid, would sustain
constant immersion at ordinary temperatures for 3600 days
(Lunge), 43 days (Le Roy), or 14 days (Richards), if taken
out every day and polished bright.
Concerning the use of aluminium in the Grove battery, which
is not a constant battery, but only used to give a strong cur-
rent for a short time, aluminium sheet one millimetre thick
will last a long time and cost only a fraction as much as thin
platinum.
Hydrochloric Acid.
This acid attacks commercial aluminium rapidly, quicker
when hot than when cold, and the concentrated quicker than
the dilute. The very pure metal, however, is attacked slowly,
showing that, as with sulphuric acid, the galvanic action of the
impurities keeping the aluminium free from a protecting layer
•of gas, has a great influence on the resistance to acids. Gase-
ous hydrochloric acid attacks the metal even at a very low
.temperature.
The presence of silicon, particularly, increases the facility
92 ALUMINIUM.
with which the metal is attacked. When silicon is present, the
graphitic silicon remains behind as a black residue, while the
combined silicon partly forms silica and partly escapes as sili-
con hydride (SiHi), having a very disagreeable smell. When
the amount of combined silicon is small, almost all of it may
thus escape. In analyzing aluminium, this loss is prevented by
keeping the acid well oxidized by bromine water, which pre-
vents the formation of the gas. On evaporating to dryness,,
after solution, and taking up with water, the graphitoidal sili-
con remains as a black crystalline residue, while the combined
silicon has all been changed to white silica. These can be
separated by washing with hydrofluoric acid, which dissolves
the silica but leaves the silicon unattacked.
If a small amount of hydrochloric acid is present in a mix-
ture of acids, it leads the attack on the metal, and the other
acids form aluminium salts by reacting on the aluminium
chloride formed. Hydrobromic, hydriodic and hydrofluoric
acids act similarly to hydrochloric. Aluminium fluoride, how-
ever, is not so soluble in water as the other halogen salts, and
the attack by hydrofluoric acid is therefore hindered by the
formation of an insoluble coating on the aluminium when the
solution passes a certain degree of concentration.
In an experiment by the writer, best commercial rolled alu-
minium was put into cold, dilute (3 per cent.) hydrochloric
acid. It was some time before any action was observable, and
then it was very slow. It lost, after cleaning, at the rate of 5S
grammes per square metre of surface per day, which was only
a little over half as much as was dissolved by cold, concentrated
nitric acid in the same time. A piece of the same metal, how-
ever, alloyed with three per cent, of nickel was rapidly attacked
under these conditions, and over thirty times as much of it was
dissolved in a given time, thus showing strikingly the influence
of a small amount of impurity.
Organic Acids, Vinegar, Etc.
Deville : " Weak acetic acid acts on aluminium in the same
CHEMICAL PROPERTIES OF ALUMINIUM. 93
way as sulphuric acid, i. e., in an inappreciable degree or with
extreme slowness. I used for the experiment acid diluted to
the strength of strongest vinegar. M. Paul Morin left a plaque
of the metal a long time in wine which contained tartaric acid
in excess and acetic acid, and found the action on it quite in-
appreciable. The action of a mixture of acetic acid and com
mon salt in solution in pure water on pure aluminium is quite
different, for the acetic acid replaces a portion of the chlorine
existing in the sodium chloride, rendering it free. However,
this action is very slow, especially if the aluminium is pure."
" The practical results flowing from these observations deserve
to be clearly defined, because of the applications which may be
made of aluminium to culinary vessels. I have observed that
the tin so often used and which each day is put in contact with
common salt and vinegar, is attacked much more rapidly than
aluminium under the same circumstances. Although the salts
of tin are very poisonous, and their action on the economy far
from being negligible, the presence of tin in our food passes un-
perceived because of its minute quantity. Under the same
circumstances aluminium dissolves in less quantity; the acetate
of aluminium formed resolves itself on boiling into insoluble
alumina or an insoluble sub-acetate, having no more taste or
action on the body than clay itself. It is for that reason and
because it is known that the salts of the metal have no appre-
ciable action on the body, that aluminium may be considered
as an absolutely harmless metal."
The low price of aluminium has within the last two years
rendered possible this application to culinary utensils foreseen
by Deville, and has led to several investigations as to its resist-
ance to the acids and salts liable to be met with in food.
Two German pharmacists, Lubbert and Roscher, conducted
tests of this kind in 1891, but their results were only qualitative,
not quantitative, and they made the mistake of using thin
aluminium foil, which averages only o.ooi inch thick, instead
of heavier sheet. The result was that they found their thin foil
totally dissolved by two days immersion in oxalic acid (1,5
94 ALUMINIUM.
and lO per cent.), gallic acid (2 per cent.), and corrosive sub-
limate (i per cent.) ; and by four days constant immersion in
I, 5 and 10 per cent, solutions of formic, acetic, butyric, lactic,,
tartaric and citric acids, pure oleic acid, 10 per cent, solutions
of palmitic or stearic acids, in 5 per cent, solutions of carbolic
acid, 4 per cent, solution of boric acid, and in pure red wine,
white wine, coffee and tea.
It has been found, however, that because of its thinness alu-
minium foil does not resist corrosion as does the heavier sheet-
metal, and while the above results may be strictly true for foil
0.00 1 inch thick, yet ordinary sheet aluminium is not attacked
to anything like such an extent. Culinary utensils are made of
sheet at least i millimetre (0.04 inch) thick, and tests of mate-
rial of this thickness made by subsequent investigators have
given very different results.
Balland* conducted tests for several months, and found that
air, water, wine, beer, cider, coffee, milk, oil, butter, fat, urine,
saliva and damp earth have less action on aluminium than on
iron, copper, lead, zinc, or tin. Vinegar and salt together at-
tack it, but so slightly as not to prevent its use for cooking; a
sheet only lost 1.3 per cent, of its weight in vinegar, and 0.2
per cent, of its weight in a 5 per cent, salt solution after four
months' immersion.
Ruppf states that he has kept different kinds of liquid and
semi-solid food in aluminium vessels for 4 to 28 days, at the
ordinary temperature, and found the metal unaltered. The
metal used contained 0.30 per cent, of iron, 0.08 silicon and
99.66 aluminum.
Prof. Geo. Lunge, | of Zurich, has made a most careful and
systematic investigation of this subject. Assisted by Ernst
Schmid, he made the following series of tests ; ordinary com-
mercial sheet aluminum from Neuhausen was used. It ana-
lyzed :
* Comptes Rendus, 1892, Vol. 114, p. 1536.
t Chronique Industrielle, June 12, 1892.
I Zeitschrift fiir angewandte Chemie, January, 1892.
CHEMICAL PROPERTIES OF ALUMINIUM. 95
Aluminium 99.20 per cent, (by difference)
Combined silicon 0.44 "
Graphitic " o.i I "
Iron 0.25 "
Copper trace.
The sheet was i minimetre thick, and was cut into strips of
a fixed size. These were first carefully cleaned by caustic soda
and sulphuric acid, and then immersed six days in the liquids
at the ordinary temperature, each liquid being tested twice to
guard againt mistakes. The following are their results, ex-
pressed as the weight dissolved per day in milligrammes per
square metre of surface exposed :
Loss of weight per day in
milligrammes per square
Liquid. i metre of surface.
Ordinary claret 47.3
" hock 51.2
Brandy 18.0
Pure 50 per cent, alcohol 10.2
Tartaric acid, 5 per cent, solution 28.2
" '■ I " " 43.0
Acetic " S " " .64.2
" " I " " 73.0
Citric " 5 " " 35-8
" I " " 31-7
Lactic " 5 " " ■■■■■ 79-5
Butyric " 5 " " 21.8
Carbolic " 5 " " 3-8
" " 1 " •• 8.2
Boric " 4 " " 29.5
Salicylic " I4 " " 105.8
Coffee (poured hot) 8.3
Tea " 00
Beer o-o
The aluminium strips used showed outward evidences of
corrosion in only a few places ; only in the case of the salicylic
acid solution had the metal lost its bright surface and become
dull. In the case of brandy and alcohol, where the quantitative
action was very slight, the surface of the aluminium showed a
few fungus-like excresences, probably formed by alumina,
caused by accidental flaws in the sheet. In the case of a wine
96 ALUMINIUM.
rich in tannin, these spots are liable to be darkened by the in-
fluence of the trace of iron dissolved from the aluminium, form-
ing tannate of iron, but the amount thus formed is infinitesmal.
The weights dissolved are so extremely small, that it may be
calculated that a canteen holding a litre could be kept full of
the strong acetic acid for 55 years before losing half its weight.
Lunge and Schmid conclude that, " the action of coffee, tea
and beer is practically zero ; that of acids and acid liquids is
more pronounced, but in the worst case too slight to cause any
alarm whatever. Nor is there the slightest danger of any in-
jurious action on the human body by such traces of aluminium
compounds, seeing that our food contains very much more than
these ; in fact, they could not act injuriously unless quantities
hundreds of times larger were regularly entering the stomach."
The only criticism we have to make of this valuable investiga-
tion is that the solutions should have been tested hot, even
boiling, as well as cold. While it is perfectly true, as remarked
by a Washington lady, that " we hope never to have occasion
to serve our families with poisoned soups or salicylic or boracic
acid stews," yet if Lunge had made the hot-liquid tests we
should, at least, have known the worst that could possibly hap-
pen to the aluminium culinary utensils.
Happily, actual experience has settled all these questions.
An aluminium sauce-pan used in the writer's family constantly
for two years, which has been used for boiling milk, cooking
oatmeal and vegetables, stewing meats and preserving several
kinds of fruits, lost less than one-quarter ounce in the whole two
years, an average of less than 15 milligrammes per day per
square metre of surface exposed, including frequent cleaning.
I have calculated that at this rate the utensil will become a fam-
ily heirloom unless accident overtakes it, for it could stand this
rate of wear for over a century before losing half its weight.
Other experiences equally as striking could be cited, and no
better proof of the suitability of aluminium for culinary utensils
could be wished. The German Minister of War, after thorough
experiments by an army commission, has adopted aluminium
CHEMICAL PROPERTIES OF ALUMINIUM. • 9/
canteens and drinking cups for the soldiers, and entire sets of
cooking utensils for use in the officers' quarters. It is the
writer's opinion that within a short time the larger part of all
the aluminium made will be needed to supply the great demand
which will arise for these culinary utensils.
Sodium Chloride.
Common salt does not, when molten, corrode aluminium, so
that it forms a good flux to melt the metal with. It does not
possess the property, like fluorspar, of dissolving alumina, but
acts simply by its fluidity to give a clean melt.
A solution of common salt acts very feebly on aluminium.
A strip of rolled aluminium immersed in a three per cent, solu-
tion at 27° C. lost weight at the rate of 394 milligrammes per
day per square metre of surface (Hunt). The writer found a
corresponding loss of 400 milligrammes per day on sheet im-
mersed in a strong brine kept at 65° C. (150° F.) At that
rate it would take nine years' constant immersion to entirely
dissolve a sheet one millimetre thick.
When an acid is present with the salt, the action is stronger
than when either is alone. Mr. Hunt found that when two
per cent, of acetic acid was added to the salt solution previously
mentioned, the corrosion was increased to 1738 milligrammes
per day. This solution will fairly represent the extreme con-
ditions to which aluminium will be subjected in domestic culi-
nary operations, and shows that the corrosion is so slight as to
be of no practical consequence, being much less than copper,
tin-plate or iron would sufifer under similar conditions.
Sea-water corrodes aluminium slightly, but much less than
iron or steel, under similar conditions. Strips of aluminium
on the sides of a wooden sailing vessel lost less than 100 milli-
grammes per square metre of surface during six months' ex-
posure (Hunt). Messrs. Yarrow & Co., on the Thames,
having in view the building of an aluminium torpedo boat for
the French government, took two plates of aluminium stiffened
by alloying with six per cent, of copper, and after weighing
7
98 ALUMINIUM.
accurately secured them on the sides of a wooden, coppered
sailing vessel, the copper being removed to make place for
the aluminium. This ship made a voyage round the world ;
then the aluminium plates were removed, weighed, and found
to have suffered no appreciable loss. As a consequence of this
result, Messrs. Yarrow proceeded with the construction of the
boat, which is the largest vessel yet built of aluminium, having
a length of sixty feet, beam nine feet three inches and a maxi-
mum speed of twenty-two knots (twenty-five and one-half
miles) per hour.
It is to be recommended, however, that aluminium hulls in-
tended for salt water should be painted, in order to reduce any
possible corrosion to a minimum.
Organic Secretions.
These act only slightly on aluminium, the degree of corrosion
being proportioned mostly to the amount of sodium chloride
present in the secretion and its degree of acidity, or, particu-
larly, of alkalinity. The saliva acts on it so slightly that alu-
minium dental plates may be worn for many years without any
appreciable corrosion. M. Charriere, a French physician, was
the first to make a small tube of it for a person on whom trache-
otomy had been performed. He found it to remain almost
unaltered by contact with purulent matter ; after a long time a
little alumina was formed on it, hardly enough to be visible.
The use of aluminium for suture wire is also highly recom-
mended ; many instruments for physician's use are being made
of aluminium, its great advantages being lightness, incorrodibil-
ity, and being so easily cleansed, particularly by antiseptic
solutions. The tarnishing of polished aluminium articles when
constantly handled is due to the perspiration, which contains
about two per cent, of sodium chloride and about an equal
quantity of organic acids. Its action is not very strong, yet
sufficient to spoil a high polish and give a visible tarnish, as
would indeed happen to almost any other metal. If, however,
the perspiration is profuse and acts on the aluminium con-
CHEMICAL PROPERTIES OF ALUMINIUM. 99
stantly while warm, a deeper corrosion results. I have seen an
aluminium ankle-stiffener, of metal about one millimetre thick,
which was worn in the heel of a boot for about a year, and was
then eaten nearly through by the corrosion due to perspiration
a little above the ankle. The shoe lining which covered it had
served to keep it constantly in contact with the perspiration,
while the temperature may have been about 85° C. This is,
however, an extreme case, and it would be interesting to know
whether steel or very stifif leather would have lasted as long_
under the same circumstances.
Caustic Alkalies.
Deville : " Solutions of caustic potash or caustic soda ict'
with great energy on aluminium, transforming it into aluminate
of potash or soda, setting free hydrogen. However, it is not
attacked by caustic potash or soda in fusion ; one may, in fact,
drop a globule of the pure metal into melted caustic soda raised
almost to red heat in a silver vessel, without observing the
least disengagement of hydrogen. Silicon, on the contrary,
dissolves with great energy under the same circumstances. I
have employed melted caustic soda to clean siliceous alumin-
ium. The piece is dipped into the bath kept almost at red
heat. At the moment of immersion several bubbles of hydro-
gen disengage from the metallic surface, and when they have
disappeared all the silicon of the superficial layer of aluminium
has been dissolved. It only remains to wash well with water
and dip it into nitric acid, when the aluminium takes a beautiful
mat.
Mallet found that the purest aluminium resists the caustic
alkaline solution better than the commercial metal. I have-
noticed the same fact in comparing aluminium of different
degrees of purity; best commercial metal withstood the action
of cold, dilute caustic potash solution seven times better than
when it contained three per cent, of copper, and seventy times
better than when two per cent, of copper and one per cent, of
zinc were present.
lOO ALUMINIUM.
Prof. A. Stutzer,* of Bonn, finds that the metal made by the
electrolytic processes dissolves much slower than that made by
the former sodium processes. He ascribes this to the latter
metal containing nearly one per cent, of sodium. This, how-
ever, can hardly be the case, because metal made by the Deville
process rarely contained more than a trace of sodium. The true
reason must be simply the greater purity of the metal now be-
ing made by electrolysis, which averages over 99 per cent, pure
for best quality metal, while the Deville metal was rarely over
98 per cent. pure.
Ammonia.
Aqua ammonia acts slowly on aluminium, producing a little
alumina, part of which remains dissolved. Ammonia gas does •
not appear to act on the metal.
Lime Water.
This acts rapidly on aluminium at first, but the resulting
calcium aluminate is insoluble in water, and is, therefore, pre-
cipitated on the metal and quickly protects it from further
action. If this coating is scraped off the action is repeated.
Solutions of Metallic Salts.
Deville : " The action of any salt whatever on aluminium may
be easily deduced from the action of its acids on that metal. '
We may, therefore, predict that in acid solutions of sulphates
and nitrates aluminium will precipitate no metal, not even
silver, as Wohler has observed. But the hydrochloric solutions
of the same metal will be precipitated, as MM. Tissier have
shown. Likewise, in alkaline solutions, silver, lead, and metals
high in the classification of the elements are precipitated. It
may be concluded from this that to deposit aluminium on other
metals by means of the battery, it is always necessary to use
acid solutions from which hydrochloric acid, free or combined,
.should be absent. For similar reasons the alkaline solutions of
* Zeitschr. fiir angewandte Chemie, 1890, No. 23.
CHEMICAL PROPERTIES OF ALUMINIUM. lOI
the same metals cannot be employed, although they give such
good results in plating common metals with gold and silver. It
is because of these curious properties that gilding and silvering
aluminium are so difficult."
These conclusions by Deville are confirmed only when using
pure aluminium; the impure metal, containing iron, silicon, or
perhaps sodium, may produce very slight precipitates in cases
where pure aluminium would produce none. Some observers
have noted different results in some cases even when using alu-
minium free from these impurities. We will therefore take up
these cases and consider them separately.
Mercury. — * Aluminium decomposes solutions of mercuric
chloride, cyanide or nitrate, mercury separating out first, then
forming an amalgam with the aluminium which is immediately
decomposed by the water, the result being alumina and mer-
cury. From an alcoholic solution of mercurous chloride the
mercury is precipitated more quickly at a gentle heat. A solu-
tion of mercurous iodide with potassium iodide is also reduced
in like manner.
Copper. — * From solution of copper sulphate or nitrate, alu-
minium separates out copper only after two days' standing, as
either dendrites or octahedra ; from the nitrate it also precipi-
tates a green, insoluble basic salt. Copper is precipitated
immediately from a solution of cupric chloride; but slower
from the solution of copper acetate. The sulphate or nitrate
solutions behave similarly if potassium chloride is also present,
and the precipitation is complete in presence of excess of alu-
minium.
Silver. — *From a nitrate solution, feebly acid or neutral,
aluminium precipitates silver in dendrites, the separation only
beginning after six hours' standing. From an ammoniacal
solution of silver chloride or chromate, aluminium precipitates
the silver immediately as a crystalline powder. Cossa con-
firms the statement as to the nitrate solution.
Lead. — * From nitrate or acetate solution the lead is slowly
* Dr. Mierzinski.
I02 ALUMINIUM.
precipitated in crystals ; an alkaline solution of lead chromate
gives precipitates of lead and chromic oxide.
Zinc. — * An alkaline solution of zinc salt is readily decom-
posed and zinc precipitated.
Margottet states that all metallic chlorides excepting those
of potassium or sodium are reduced from solution. This state-
ment can hardly include chlorides of magnesium or lithium,
since magnesium precipitates alumina from solutions of alu-
minium salts. Alkaline or ammoniacal solutions are more
easily decomposed than acid solutions ; in alkaline solutions
the cause being the facility with which aluminates of the alka-
lies are formed.
Alkaline Chlorides. — A solution of sodium or potassium
chlorides is not appreciably affected by pure aluminium, either
cold or warm. However, rather impure aluminium which was
packed in a case with saw-dust and kept wet with sea-water for
two weeks was corroded ; whether the result would have been
the same without the presence of the saw-dust or with purer
aluminium, I cannot say.
Aluminium Salts. — It is a curious fact that a solution of alu-
minium chloride will attack aluminium, forming a basic-chloride
with evolution of hydrogen. A solution of alum does not attack
aluminium, but if sodium chloride is added it is dissolved with
evolution of hydrogen. It is interesting to note that while
neither of these salts alone attacks aluminium, the mixture of
the two does.
Fluorspar.
Fluorspar on being melted gives off a little hydroflouric acid
vapor, caused by the action of the hydroscopic moisture in it.
This vapor will attack aluminium, forming fluoride. Aside
from this slight action, the molten fluorspar has no action on
the aluminium. It has, however, the property of dissolving
a small proportion (about 2 per cent.) of alumina, and this
action causes it to be a very efficient flux, because small
* A. Cossa, Bull, de la Soc. Chim., 1870, p. 199.
CHEMICAL PROPERTIES OF ALUMINIUM. IO3
globules of aluminium are usually encrusted with a thin film
of alumina which prevents them from running together to a but-
ton. The fluorspar, by dissolving this coating and affording a
fluid mass, fluxes the separated globules together. It is often
used in connection with cryolite and common salt.
Cryolite.
Melted cryolite is a very good flux for aluminium, for the
same reason as described under fluorspar. It can, however,
dissolve over 20 per cent, of alumina, and is therefore that
much more efficient as a fluxing agent. At a temperature
above the melting point of copper it attacks the aluminium
itself, if it is put into it finely divided, but the metal en masse
is not sensibly attacked. The result of this attack must be the
formation of a sub-fluoride, possibly AIF2.
Silicates and Borates.
Neither of these classes of compounds can be used as fluxes
or slags in working aluminium, since they both rapidly corrode
the metal. Deville had little difficulty in decomposing these
salts so completely with metallic aluminium that he isolated
silicon and boron. If aluminium is melted in an ordinary
glass vessel it attacks it, setting free silicon from silica, forming
an aluminate with the alkali present and an alloy with the sili-
con set free. Aluminium melted under borax is rapidly dis-
solved, an aluminium borate being formed. It is thus seen
that the common metallurgic slags are altogether excluded
from the manufacture of aluminium, and also that it is an im-
possibility to manufacture pure aluminium direct from minerals
containing silica. The result of reducing kaolin, for instance,
would inevitably be highly siliceous aluminium, from which
there is no known method of separating out pure aluminium.
These facts also point to the importance of keeping molten
aluminium from contact with the ordinary siliceous refractory
materials in working it. Even the best quality plumbago
crucibles will increase the percentage of silicon in commercial
I04 ALUMINIUM.
aluminium at least 0.25 per cent, at one melting. Magnesia
brick linings and magnesia-lined crucibles should be used for
melting it in.
Nitre.
Deville : " Aluminium may be melted in nitre without under-
going the least alteration, the two materials rest in contact
without reacting even at a red heat, at which temperature the
salt is plainly decomposed, disengaging oxygen actively. But
if the heat is pushed to the point where nitrogen itself is disen-
gaged, there the nitre becomes potassa, a new affinity becomes
manifest, and the phenomena change. The metal then com-
bines rapidly with the potassa to give aluminate of potash.
The accompanying phenomenon of flagration often indicates a
very energetic reaction. Aluminium is continually melted with
nitre at a red heat to purify it by the oxygen disengaged, with-
out any fear of loss. But it is necessary to be very careful in
doing it in an earthen crucible. The silica of the crucible is
dissolved by the nitre, the glass thus formed is decomposed by
the aluminium, and the silicide of aluminium formed is then
very oxidizable, especially in the presence of alkalies. The
purification by nitre ought to be made in an iron crucible well
oxidized by nitre inside."
If finely divided aluminium is mixed with nitre and brought
to a red heat, the metal is oxidized with the production of a
fine blue flame. (Mierzinski.) Nitre is also used sometimes
in the composition of aluminium flash-light powders.
Alkaline Sulphates and Carbonates.
Tissier : "Only 2.65 grammes of aluminium introduced into
melted red-hot sodium sulphate (NajSOj) decomposed that
salt with such intensity that the crucible was broken into a
thousand pieces, and the door of the furnace blown to a dis-
tance. Heated to redness with alkaline carbonate, the alu-
minium was slowly oxidized at the expense of the carbonic
acid, carbon was set free, and an aluminate formed. The re-
action takes place without deflagration."
chemical properties of aluminium. i05
Metallic Oxides.
Tissier Brothers made a series of experiments on the action
of aluminium on metallic oxides. Aluminium leaf was care-
fully mixed with the oxide, the mixture placed in a small por-
celain capsule and heated in a small earthen crucible, which
served as a muffle. The results were as follows :
Manganese dioxide. — No reaction.
Zinc oxide. — No reaction even at white heat.
Ferric oxide. — By heating to white heat one equivalent of
ferric oxide and three of aluminium, the reaction took place
with detonation, and by heating sufficiently we obtained a
metallic button, well melted, containing 69.3 per cent, of iron
and 30.7 per cent, of aluminium. Its composition corresponds
very nearly to the formula AlFe. It would thus appear that
the decomposition of ferric oxide will not pass the limit where
the quantity of iron reduced is sufficient to form with the alu-
minium the alloy AlFe.
Lead oxide. — We mixed two equivalents of litharge with one
of aluminium, and heated the mixture slowly up to white heat,
when the latter reacted on the litharge with such intensity as
to produce a strong detonation. We made an experiment with
fifty grammes of litharge and 2.9 grammes of aluminium leaf,
when the crucible was broken to pieces and the doors of the
furnace blown off.
Copper oxide. — Three grammes of black oxide of copper
mixed with 1.03 grammes of aluminium detonated, producing
a strong explosion, when the heat reached whiteness.
Beketoff"* reduced baryta (BaO) with metallic aluminium in
excess, and obtained alloys of aluminium and barium contain-
ing in one case twenty-four per cent., in another thirty-three
per cent, of barium.
If any of the metallic oxides are fluxed, as by being dis-
solved in cryolite, metallic aluminium reduces them to metal at
once. Messrs. Green and Wahl have patented this method of
* Bull, de la Soc. Chimique, 1887, p. 22.
I06 ALUMINIUM.
producing pure metallic manganese, which is at present being
put into operation in Philadelphia on a commercial scale.
Miscellaneous Agents.
Phosphate of lime. — Tissier Brothers heated to whiteness a
mixture of calcium phosphate with aluminium leaf, without the
metal losing its metallic appearance or any reaction being
noted.
Hydrogen. — This gas appears to have no action on alumin-
ium, except to be dissolved in it in a moderately large quantity.
Chlorine. — Gaseous chlorine attacks the metal rapidly. Alu-
minium foil heated in an atmosphere of chlorine takes fire and
burns with a vivid light.
Bromine, iodine, act similarly to chlorine.
Fluorine. — Fluorine gas forms a thin coating of fluoride which
prevents a deeper attack. If the metal is at a dark-red heat, a
violent incandescence ensues, and the attack is very energetic.
Under the microscope the residue is seen to be globules of alu-
minium covered with uncrystallized fluoride.
Silver chloride. — Fused silver chloride is decomposed by
aluminium, the liberated silver as well as the excess of alumin-
ium being melted by the heat of the reaction.
Mercurous chloride. — If vapors of mercurous chloride are
passed through a tube in which some hot aluminium is placed,
mercury is separated out, aluminium chloride deposits in the
cooler part of the tube, and the aluminium is melted by the
heat developed.
Carbonic oxide. — Aluminium acts on this gas, forming alu-
mina and setting free carbon. Prof. Arnold proved this by
taking molten steel of a known content of carbon, and after
adding to it several per cent, of aluminium, he passed a current
of this gas through it for one hour. A sample of the metal
subsequently analyzed showed one-third more carbon than
before the treatment. This reaction is one of the causes of
the advantage of adding aluminium to molten steel, as it thus
jemoves one of the gases which form blow-holes in the cast-
ings.
CHAPTER V.
PROPERTIES AND PREPARATION OF ALUMINIUM COMPOUNDS.
In this chapter we propose to note in rather condensed form
the prominent characteristics of the various aluminium com-
pounds, with an outline of the methods by which they can be
produced, reserving for another chapter, however, the prepara-
tion of those salts which are now being manufactured on a
commercial scale for purposes of further treatment for alumin-
ium. I do not propose this as a substitute for the various
chemical treatises on this subject, but simply to add to the
completeness of this work in order that a fair understanding of
the other parts of the book may not be missed because data of
this nature are not immediately at hand. Parts of this chapter
are taken from M. Margottet's treatise on aluminium, in
Fremy's Enclycopedie Chimique.
General Considerations.
Position of aluminium in the periodic classification of the ele-
ments.— Mendeleeff places aluminium in his third family of
elements, it being preceded by boron, and followed by the rare
elements scandium, gallium, yttrium, indium, didymium, erbium
and thallium. These elements all form oxides of the same
general form, R2O3, and their other chemical compounds are
■correspondingly similar. As we have zinc, cadmium and mer-
cury as the analogues of magnesium in the second group, so we
have gallium, indium and thallium as the corresponding ana-
logues of aluminium in the third group. Unfortunately, these
elements are so rare that we are not so familiar with their prop-
erties as we could wish. We can notice, however, that as the
atomic weight increases the specific gravity and the atomic
(107 )
I08 ALUMINIUM.
volume increase also, while the compounds formed by these
metals become more easily decomposable. For instance :
Element. Atomic Weight. Specific Gravity. Atomic Volume.
Boron ii 2.5 4.5
Aluminium 27 2.7 10
Gallium 70 5.9 12
Indium 113 7.4 14
Thallium 204 11.8 17
Structure of aluminium compounds. — Aluminium has until re-
cently been regarded as a quadrivalent element, for the reason
that no compound was known whose molecule contained less than
two atoms of aluminium combined with six atoms of a mono-
valent element. Thus, the oxide was AI2O3, the chloride AhCle,,
etc. It was, therefore, supposed that in the molecule of every
aluminium compound the two atoms of aluminium were held
together by an exchange of one bond, and since each atom had
three bonds left over, it was supposed that each single alumin-
ium atom had four bonds or affinities. The composition of the
oxide and chloride were therefore represented graphically as.
follows :
r O -, Cl cl
0 = A1— A1 = 0 Cl — Al — Al — Cl
A dl
The two atoms of aluminium, having six free affinities, were
spoken of as a " double hexad-atom."
All this reasoning, however, has broken down since the dis-
covery of compounds containing only one atom of aluminium!
in a molecule, and in which the aluminium is undoudtedly tri-
valent; such are the organic salts A^CHa),, A1(C2H5)3,.
A1(C5H702)3. In the latter salt, the vapor density corresponds
to the formula given at only 45° above its melting point-
Even aluminium chloride itself has been proven to have the
formula AlCls when its vapor density is taken at a temperature
above 800°. We are therefore constrained to drop the former
PROPERTIES OF ALUMINIUM COMPOUNDS. IO9
ideas, and consider aluminium as tri-valent. The graphic
formulae given above must then be written
Cl
0 = A1 — O — Al = o Cl — Al — Cl
The tri-valency of aluminium is also required by its position
in the list of elements. Thus we have, taking the elements
immediately preceding and following it :
Atomic Weight. Valence in organic salts
Sodium 23 I
Magnesium 24 2
Aluminium 27 3
Silicon 28 4
Phosphorus 31 3
Sulphur 32 2
Chlorine 353^ i
Aluminium acts as a feeble base or a rather strong acid. As
a base it has many analogies with iron in ferric compounds.
For instance, the oxides AlzOs and FcjOg crystallize in the same
iorms, rhombohedra, with almost exactly the same fundamen-
tal angles, while the native hydrous oxides AI2O3.H2O and
Fe^Os.HjO, both crystallize in the orthorhombic system with
very similar angles and cleavages. As an acid, it forms com-
pounds analogous to ferric and chromic acids. For instance :
Aluminate of iron ^. FeAl^O,.
Ferrate " " FeFejOj.
Chromate " " FeCr^O^.
These all crystallize in isometric octahedra, and are in every
respect very similar minerals. The salts in which aluminium
acts as an acid are called aluminates. They may be written
as salts of aluminic acid, HjAljO^, but there are other alumin-
ates known having a smaller proportion of alumina, and it is
much more convenient to express the composition of all these
aluminates by the dualistic method. Thus, there are known to
exist (see Bayer's method of treating bauxite, next chapter.)
I lO ALUMINIUM.
Al203.Na20.
AljOj.zNa^O.
Al,03.3Na,0.
AljOs.eNa^O.
the writing of which formulae by the rationalistic method would
be very cumbersome.
The normal or neutral salts of aluminium as a base may be
regarded as the acid with its hydrogen replaced by alumin-
ium. Thus :
Acid. Salt.
3HCI AlCls
3QH,0, AlCQHsO,),
3H,S0t A1,(S0J3
HaPjO^ AIP2O4
Aluminium, however, has a great tendency to form basic
salts when these neutral salts are put in contact with an excess
of aluminium or alumina. It is most convenient to write the
formulae of these by the dualistic method. Thus we have :
Normal sulphate, AI2O3.3SO3.16HJO. Basic sulphate, 2AI2O3.SO3.10H2O.
Normal acetate, AI2O3.6C2H2O. Basic acetate, Al20s.2C2H.^0.2H20.
While the writer has no intention of going back to the
duaHstic theories which such formulae were first used to repre-
sent, yet he takes the liberty of using these formulas to represent
the empirical composition of these salts, because of their con-
venience, and without attaching to them any theories as to the
internal structure of the molecules.
General methods of formation and properties. — Hydrated alu-
mina, which has not been too strongly heated, dissolves in
strong acids, forming salts which are mostly soluble in water.
In the feebler acids and in all organic acids it is completely in-
soluble. The salts of these latter acids are formed best by de-
composing solution of aluminium sulphate with the barium or
lead salt of the acid in question. Most aluminium salts are
soluble in water and rather difficult to crystallize : the few in-
soluble salts are white, gelatinous, and similar to the hydrate
PROPERTIES OF ALUMINIUM COMPOUNDS. Ill
in appearance. In the neutral salts the acid is loosely held,
for their solution strongly reddens litmus paper and their action
is as if part of the acid were free in the salt. For instance, a
solution of alum attacks iron giving ofi hydrogen, a soluble
basic salt of aluminium being formed as well as sulphate of
iron. The neutral salts of volatile acids give ofif acid simply by
boiling their solutions, basic salts being formed. An aqueous
solution of aluminium chloride loses its acid almost completely
on evaporation. Gentle ignition is sufficient in most cases to
completely decompose aluminium salts. Hydrated alumina
dissolves easily in caustic alkali, forming soluble aluminates ;
with baryta two aluminates are known, one soluble, the other
not ; all other known aluminates are insoluble.
Chemical reactions. — Neutral solutions of aluminium salts
react as follows with the common reagents :
Hydrogen sulphide produces no precipitate.
Ammonium sulphide precipitates aluminium hydrate with
separation of free sulphur.
Caustic potash or soda precipitates aluminium hydrate, solu-
ble in excess.
Aqua ammonia precipitates aluminium hydrate insoluble in
excess, especially in presence of ammoniacal salts.
Alkaline carbonates precipitate aluminium hydrate insoluble
in excess.
Sodium phosphate precipitates white gelatinous aluminium
phosphate, easily soluble in acids or alkalies.
Before the blowpipe most aluminium compounds are infusible
or are quickly converted into infusible alumina. In the light-
colored, infusible compounds, the aluminium may be recognized
by giving a beautiful, enamel-like blue color (Thenard's blue)
when moistened with dilute solution of cobalt nitrate and
ignited in a pure oxidizing flame. Light-colored fusible com-
pounds will also give the same reaction, but in them the ab-
sence of silica, boric and phosphoric acids must be proven by
other tests before the presence of aluminium can be asserted
with certainty.
i i 2 aluminium.
Aluminium Oxide.
Commonly called alumina. Composition Al^Oj, and contains
52.95 per cent, of aluminium when perfectly pure. Colorless
corundum is a natural pure alumina, in which state it is infusible
at ordinary furnace heats, insoluble in acids, has a specific
gravity of 4, and is almost as hard as the diamond. To get
this into solution it must be first fused with potassium hydrate
or bisulphate. The alumina made by igniting aluminium hy-
drate or sulphate is a white powder, easily soluble in acids if
the ignition has been gentle, but becoming almost insoluble if
the heat has been raised to whiteness. The specific gravity of
this ignited alumina also varies with the temperature to which
it has been raised; if simply to red heat, it is 3.75 ; if to bright
redness, 3.8; and if to whiteness, 3.9. In the last case it ac-
quires almost .the hardness of corundum. It can be melted to a
clear, limpid liquid in the oxyhydrogen blow-pipe ; after cool-
ing it forms a clear glass, often crystallized. Small artificial
crystals of alumina, exactly similar to the natural ones, have
been obtained by dissolving powdered alumina in fused boric
oxide and then volatilizing the latter by an intense heat.
Fluorine gas acts energetically on powdered alumina. As
soon as it comes in contact, the whole mass becomes incandes-
cent, forming a fluoride and disengaging oxygen. The reaction
A\A + 6F = 2AIF3 + 30.
disengages i,ioo calories of heat per kilogramme of fluorine
acting. Gaseous chlorine does not act on it even at redness,
but if carbon is present at the same time aluminium chloride is
formed. Similarly, although neither carbon nor sulphur, alone
or mixed together, acts on alumina, carbon bisulphide converts
it into aluminium sulphide.
The preparation of alumina for commercial purposes is de-
scribed at length in the next chapter.
properties of aluminium compounds. ii 3
Aluminium Hydrates.
There are three natural hydrates of aluminium, which may-
be briefly described as follows :
Diaspore, formula AI2O3.H2O or Al202.(OH)j, containing 85
per cent, of alumina, occurs in crystalline masses as hard as
quartz, with a specific gravity of 3.4. Bauxite, approximately
of the formula AI2O3.2H2O or Al20.(OH)4, with the aluminium
replaced by variable quantities of iron. If perfectly pure, it
would contain 74 per cent, of alumina. Hydrochloric acid re-
removes from it only the iron ; heated with moderately dilute
sulphuric acid it gives up its alumina; a concentrated alkaline
solution also dissolves the alumina. Calcined with sodium
carbonate it forms sodium aluminate without melting. Gibbsite,
formula AI2O3.3H2O or Al2(OH)6, containing, when pure sixty-
five per cent, of alumina, is a mineral generally stalactitic,
white, and with a specific gravity of 2.4. It loses two-thirds of
its water at 300° and the rest at redness.
The artificial hydrates are of two kinds, the soluble and in-
soluble modifications. The latter is the common hydrate, such
as is obtained by adding ammonia to a solution containing alu-
minium. The precipitate is pure white, very voluminous, and
can be washed free from the salts with which it was precipi-
tated only with great difficulty. Its composition is Al2(OH)6,
corresponding to the mineral gibbsite. It is insoluble in water,
but easily soluble in dilute acids or alkali solutions. It dis-
solves in small quantity in ammonia, but the presence of am-
monia salts counteracts this action. When dissolved in caustic
potash or soda the addition of ammoniacal salts reprecipitates it.
It loses its water on heating, in the same manner as gibbsite.
Many other properties of this hydrate, and its manufacture on
a large scale, are given in the next chapter. The soluble modi-
fication can only be made by complicated processes, too long
to be described here, and is principally of use in the dyeing
industries ; a full description can be found in any good chemi-
cal dictionary.
8
114 aluminium.
Aluminates.
Potassium aluminate. — Formula KjAljO^, crystallizes with
three molecules of water, the crystals containing forty per cent,
alumina, 37.5 per cent, potassa and 21.5 per cent, of water. It
is formed when precipitated alumina is dissolved in caustic
potash, or by melting together alumina and caustic potash in a
silver dish and dissolving in water. If the solution is evapo-
rated in vacuo, brilliant hard crystals separate out. They are
soluble in water but insoluble in alcohol.
Sodium aluminate has not been obtained crystallized. Ob-
tained in solution by dissolving alumina in caustic soda or by
fusing alumina with caustic soda or sodium carbonate and dis-
solving in water. If single equivalents of carbonate of soda
and alumina are used, the aluminate seems to have the com-
position NajAljOi) if an excess of soda is used, the solution
appears to contain Al2(0Na)e, or AljOj.sNajO. Dr. Bayer
thinks that Al203.2Na20 and Al203.6Na20 are also possible in
solution. If a solution of sodium aluminate is concentrated to
20° or 30° B., alumina separates out; if carbonic acid gas is
passed through it, aluminium hydrate is precipitated. For a
description of its' manufacture on a large scale, see next
chapter.
Barium aluminate. — Formula BaAl^Oi. Deville prepared it
by calcining a mixture of nitrate or carbonate of barium with •
an excess of alumina, or by precipitating sulphate of aluminium
in solution by baryta water in excess. The aluminate is solu-
ble in about ten times its weight of water and crystallizes out
on addition of alcohol. The crystals contain four molecules of
water. Gaudin obtained it by passing steam over a mixture of
alumina and barium chloride, or of alumina, barium sulphate,
and carbon, at a red heat. Tedesco claimed that by heating
to redness a mixture of alumina, barium sulphate, and carbon,
barium aluminate was extracted from the residue by washing
with water. He utilized this reaction further by adding solu-
tion of alkaline sulphate, barium sulphate being precipitated
PROPERTIES OF ALUMINIUM COMPOUNDS. II5
(which was used over), while alkaline aluminate remained in
solution.
Calcium, aluminate. — Lime water precipitates completely a
solution of potassium or sodium aluminate, insoluble gelatinous
calcium aluminate being formed, of the formula A]2(06Ca3) or'
AljOs.sCaO. At a red heat it melts to a glass, which, treated
after cooling with boiling solution of boric acid, affords a com-
pound appearing to contain aAljOj-SCaO. (Tissier.) Lime
water is also completely precipitated by hydrated alumina, the-^^
compound formed having the composition CaAljOi or AI2O3.--
CaO. Also, by igniting at a high temperature an intimate
mixture of equal parts of alumina and chalk, Deville obtained^
a fused compound corresponding to the formfila CaAljO^.
Zinc aluminate occurs in nature as the mineral Gahnit^,
formula ZnALOi. Berzelius has remarked that when a solution
of zinc oxide in ammonia and a saturated solution of alumina
in caustic potash are mixed, a compound of the two oxides is
precipitated, which is redissolved by an excess of either alkali.
Copper aluminate. — On precipitating a dilute solution of
sodium aluminate with an ammoniacal solution of copper sul-
phate, the clear solution remaining contained neither copper
nor aluminium. Whether the precipitate contained these com-
bined as an aluminate I did not determine.
Magnesium aluminate occurs in nature as Spinel; iron
aluminate as Hercynite; beryllium aluminate as Chrysoberyl.
The first mentioned has been lately proven to exist in small
quantities in crystallized blast-furnace slags.* Ebelman has
also prepared it in small crystals by dissolving alumina and
magnesia in fused boric oxide and driving off some of the
solvent by intense heat.
Aluminium Chloride.
Formula AICI3, contains 20.2 per cent, of aluminium. The
commercial chloride is often yellow or even red from the pres-
ence of iron, but the pure salt is quite white. It absorbs water
* P. W. Shimer. Journal Am. Chemical Soc, 1894, p. 501.
Il6 ALUMINIUM.
very rapidly from the air. It usually sublimes without melting,
■especially when in small quantity, but if a large mass is rapidly
ieated, it may melt and even boil, but its melting point is very
close to its boiling point. Friedel and Crafts have determined
the melting point as 178°, boiling point 183°. When sublimed
it deposits in brilliant, hexagonal crystals. A current of steam
rapidly decomposes it into alumina and hydrochloric acid.
Oxygen disengages chlorine from it at redness, but decomposes
it incompletely. Potassium or sodium decomposes it ex-
plosively, the action commencing below redness. Anhydrous
sulphuric acid converts it into aluminium sulphate. Alumin-
ium chloride combines with many other chlorides, forming the
double salts.
On dissolving this salt in water, or by dissolving alumina in
hydrochloric acid, a solution is obtained which on evaporation
deposits crystals having the formula AICI3.6H2O. If these
crystals are heated, they decompose, losing both water and
acid and leaving alumina. Thus it is not possible to obtain
anhydrous aluminium chloride by evaporating its solution, and
the anhydrous salt must be made by other methods, detailed at
length in the next chapter.
Aluminium-Sodium Chloride.
formula AlClj.NaCl contains 14 per cent, of aluminium.
The commercial salt is often yellow or brown from the presence
,of ferric chloride, but the pure salt is perfectly white. Its melt-
ing point has been generally stated to be 180°, but Mr. Baker,
<chemis.t for the Aluminium Company of London, states that
-when .the absolutely pure salt is warmed it melts at 125° to
130°. Xhat chemists should for thirty years have made an
.error of this magnitude seems almost incredible, and it would
be satisfactory if Mr. Baker would advance some further in-
formation than the bare statement above. This salt volatilizes
at a red heat without decomposition. It is less deliquescent in
the air .than aluminium chloride, and for this reason is much
icagier .to handle on a large scale. It is recently stated that the
PROPERTIES OF ALUMINIUM COMPOUNDS. 11/
absolutely pure salt deteriorates less than the impure salt in the
air, and the inference is drawn that perhaps the greater deli-
quescence of the impure salt is due to the iron chlorides pres-
ent. Its solution in water behaves similarly to that of alumin-
ium chloride ; it cannot be evaporated to dryness without
decomposition, the residue consisting of alumina and sodiun:i
chloride.
The manufacture of this double salt on a large scale is de-
scribed in the next chapter. It may be prepared in the labora-
tory by melting a mixture of the two component salts in the
proper proportions. A similar salt with potassium chloride
may be prepared by exactly analogous reactions.
Aluminium-Phosphorus Chloride.
Formula 2AICI3.PCI5, contains 9 per cent, of aluminium. It
is a white salt, easily fusible, volatilizes only about 400° and
sublimes slowly, fumes in the air and is decomposed by water.
Produced by heating the two chlorides together or by passing
vapor of phosphorus perchloride over alumina heated to redness.
Aluminium-Sulphur Chloride.
Formula 2AICI3.SCI4, contains 12.2 per cent, of aluminium.
It forms a yellow crystalline mass, fuses at 100°, may be dis-
tilled without change, and is decomposed by water. May be
obtained by distilling a mixture of aluminium chloride and
ordinary sulphur chloride, SClj.
Aluminium-Selenium Chloride.
Formula 2AlCl3.SeCl4. Obtained by heating the separate
chlorides together in a sealed tube, when on careful distillation
the less volatile double chloride remains. It is a yellow mass,
melting at 100° and decomposed by water.
Aluminium-Ammonium Chloride.
Formula 2AICI3.3NH3. Solid aluminium chloride absorbs
ammonia in large quantity, the heat developed liquefying the
Il8 ALUMINIUM.
resulting compound. It may be sublimed in a current of
hydrogen, but loses ammonia thereby and becomes 2AICI3.NH3.
Aluminium-Chlor-sulphydride.
Formed by subliming aluminium chloride in a current of
hydrogen sulphide. A current of hydrogen removes the ex-
cess of the gas used, leaving on sublimation fine colorless
crystals. In air it deliquesces rapidly and loses hydrogen
sulphide.
Aluminium-Chlor-phosphydride.
Apparently of the formula 6AICI3.PH3. If phosphuretted
hydrogen is passed over cold aluminium chloride very little is
absorbed, but at its subliming point it absorbs a large quantity,
the combination subliming and depositing in crystals. It is
decomposed by water or ammonium hydrate, disengaging
hydrogen phosphide.
Aluminium Bromide.
Formula AlBrg, containing lo.i per cent, of aluminium. It
is colorless, crystalline, melts at 93° to a clear fluid which boils
at 260°. It is still more deliquescent than aluminium chloride.
At a red heat in contact with dry oxygen, it evolves bromine
and forms alumina ; it is also decomposed slowly by the oxy-
gen of the air. It dissolves easily in carbon bi-sulphide, the
solution fuming strongly in the air. It reacts violently with
water, the solution on evaporation depositing the compound
AlBr3.6H20. The same result is attained by dissolving alumina
in hydrobromic acid and evaporating. This hydrated chloride
is decomposed by heat, leaving alumina. The specific gravity
of solid aluminium bromide is 2.5.
This compound is obtained by heating aluminium and bro-
mine together to redness, or by passing bromine vapor over a
mixture of alumina and carbon at bright redness.
Aluminium Iodide.
Formula AII3, containing 6.6 per cent, of aluminium. This
PROPERTIES OF ALUMINIUM COMPOUNDS. II 9
compound is a white solid, fusible at 125°, and boils at 350°.
It dissolves easily in carbon bisulphide, the warm saturated
solution depositing it in crystals on cooling. It dissolves also
in alcohol and ether. Its behavior towards water is exactly
analogous to that of aluminium bromide. It is prepared by
heating iodine and aluminium together, with special precau-
tions to avoid explosion.
Aluminium Fluoride.
Formula AIF3, containing 32.7 per cent, of aluminium. It
is sometimes obtained in crystals which are colorless and
slightly phosphorescent. They are insoluble in acids, even in
boiling sulphuric, and boiling solution of potash scarcely at-
tacks them ; they can only be decomposed by fusion with
sodium carbonate at a bright red heat. Melted with boric
acid, aluminium fluoride forms crystals of aluminium borate.
L. Grabau describes the aluminium fluoride which he obtains
in his process as being a white powder, unalterable in air,
unaffected by keeping, insoluble in water, infusible at redness,
but volatilizing at a higher temperature.
Deville first produced this compound by acting on alumin-
ium with silicon fluoride at a red heat. He afterwards obtained
it by moistening pure calcined alumina with hydrofluoric
acid, drying and introducing into a tube made of gas carbon,
protected by a refractory envelope. The tube was heated to
bright redness, a current of hydrogen passing through mean-
while to facilitate the volatilization of the fluoride. Brunner
demonstrated that aluminium fluoride is formed and volatilized
when hydrofluoric acid gas is passed over red-hot alumina.
Finally, if a mixture of fluorspar and alumina is placed in car-
bon boats, put into a carbon tube, suitably protected, heated to
whiteness and gaseous hydrofluoric acid passed over it, alu-
minium fluoride will volatilize and condense in the cooler part
of the tube in fine cubical crystals, while calcium fluoride re-
mains in the boats.
i20 aluminium.
Aluminium Fluorhydrate.
When calcined alumina or kaolin is treated with hydrofluoric
acid, alumina being in excess, soluble fluorhydrate of alumin-
ium is formed, which deposits on evaporating the solution. It
has the formula 2AIF3.5H2O, and easily loses its water when
heated.
Aluminium-Hydrogen Fluoride.
If to a strongly acid solution of alumina in hydrofluoric acid
alcohol is added, an oily material separates out and crystallizes,
having the formula 3AIF3.2HF.5H2O. If the acid solution is
simply evaporated, acid fumes escape and a crystalline mass
remains which, washed with boiling water and dried, has the
formula 4AIF3.HF.10H2O. On heating these compounds to
400° or 500° in a current of hydrogen, pure amorphous alu-
minium fluoride remains. The acid solution of alumina first
used seems to contain an acid of the composition AIF3.3HF,
which is capable of forming salts with other bases. Thus, if
this solution is neutralized with a solution of soda, a precipitate
of artificial cryolite, AlFs.sNaF, falls. The similar potash
compound is formed in the same way.
Aluminium-Sodium Fluoride.
Formula AlFs.sNaF, containing 12.85 P^r cent, of aluminium,
occurs native as cryolite, a white mineral with a waxy appear-
ance, as hard as calcite, specific gravity 2.9, melting below
redness and on cooling looking like opaque, milky glass. If
kept melted in moist air, or in a current of steam, it loses
hydrofluoric acid and sodium fluoride and leaves a residue of
pure alumina. When melted it is decomposable by an electric
current or by sodium or magnesium. It is insoluble in water,
unattacked by hydrochloric but decomposed by hot sulphuric
acid. The native mineral is contaminated with ferrous carbon-
ate, silica, phosphoric and vanadic acids. An extended de-
scription of its utilization, manufacture, etc., will be found in
the next chapter.
PROPERTIES OF ALUMINIUM COMPOUNDS. 121
A native compound having the formula sAlFj.jNaF is snow-
white, very similar to cryolite in appearance and properties,
except that it crystallizes in a different form and is more
fusible. It is called Chiolite. The mineral Pachnolite is also
similar, except that part of the sodium is displaced by calcium.
Aluminium Sulphide.
Formula AI2S3, containing 36 per cent, of aluminium. The
pure salt is light yellow in color and melts at a high tempera-
ture. In damp air it swells up and disengages hydrogen sul-
phide, forming a grayish white powder ; it decomposes water
very actively, forming hydrogen sulphide and ordinary gela-
tinous aluminium hydrate. Steam decomposes it easily, at red
heat forming amorphous alumina, which is translucent and very
hard. Gaseous hydrochloric acid transforms it into aluminium
chloride. Elements having a strong affinity for sulphur reduce
it, setting free aluminium, but it is doubtful if hydrogen or
carburetted hydrogen has this efifect.
It may be formed by throwing sulphur into red-hot alumin-
ium, or by passing sulphur vapor over red-hot aluminium.
Traces only of aluminium sulphide are formed by passing
hydrogen sulphide over ignited alumina, but carbon-bisulphide
vapor readily produces this reaction. For details of its forma-
tion see next chapter.
Double sulphides of aluminium and sodium or potassium,,
similar in composition to the double chlorides, may be made
by melting the two sulphides together, or, more easily, by add-
ing sodium or potassium carbonate to the ignited alumina
which is in process of conversion into sulphide. These salts
are easily fusible and nearly unchangeable in the air, but a
more detailed description of them is wanting. They are said
to be quite suitable for electrolytic decomposition. (See
Bucherer's electrolytic process.)
Aluminium sulphide has recently come into use in chemical
laboratories as a very convenient means of generating hydrogen
sulphide. A London chemical firm manufactures it by stirring
122 ALUMINIUM.
aluminium into molten sulphide of lead ; the lead separating
out sinks to the bottom, while the aluminium sulphide floats.
The sulphide is sold at $0.6o per pound, and is said to gen-
erate the gas as cheaply as by the ordinary methods.
Aluminium Selenide.
When aluminium is heated in selenium vapor, the two ele-
ments combine with incandescence, producing a black powder.
In the air this powder evolves the odor of hydrogen selenide ;
in contact with water it disengages that gas abundantly, and
furnishes a red deposit of selenium along with aluminium
hydrate. When a solution of an aluminium salt is treated with
an alkaline poly-selenide, a flesh-colored precipitate falls, the
composition of which is not known, which is decomposed at
redness, leaving aluminium.
Aluminium Borides.
AIB2, containing 55.1 per cent, of aluminium, was first ob-
tained by Deville and Wohler by heating boron in contact with
aluminium, or by reducing boric acid with the latter metal, the
action not being long continued. Also, if a current of boron
trichloride with carbonic oxide is passed over aluminium in
boats in a tube heated to redness, aluminium chloride volatil-
izes and there remains in the boats a crystalline mass, cleav-
able, and covered with large hexagonal plates of a high metal- '
lie lustre. To remove the aluminium present in excess, the
mass is treated with hydrochloric acid and then with caustic
soda. The final residue is composed of hexagonal tablets, very
thin but perfectly opaque, of about the color of copper. These
crystals do not burn in the air, even if heated to redness, but
their color changes to dark-gray. They burn in a current of
chlorine, giving chlorides of the two elements contained in
them. They dissolve slowly in concentrated hydrochloric acid
or in solution of caustic soda ; nitric acid, moderately concen-
trated, attacks them quickly.
AlBs, containing 45 per cent, of aluminium, has been ob-
PROPERTIES OF ALUMINIUM COMPOUNDS. 1 23
tained by Hampe by heating aluminium with boric acid for
three hours at a high temperature, carbon being carefully kept
away. On cooling very slowly, the upper part of the fusion is
composed of aluminium borate, the centre is of very hard
alumina containing a few black crystals of aluminium boride,
while at the bottom is a button of aluminium also containing
these crystals. To free these crystals, the aluminium is dis-
solved by hydrochloric acid. These crystals are the compound
sought for, and contain no other impurity than a little alumina,
which can be removed by boihng sulphuric acid. These puri-
fied crystals are black, but are thin enough to show a dark-red
by transmitted light. Their specific gravity is 2.5, they are
harder than corundum, but are scratched by the diamond.
Oxygen has no action on them at a high temperature, solution
of caustic potash or hydrochloric acid does not attack them,
boiling sulphuric acid has scarcely any action, but they dissolve
completely in warm, concentrated nitric acid.
If the operation by which this product is made is conducted
in the presence of carbon, the compound formed contains less
aluminium and also some carbon. Its composition corresponds
to the formula Al3C2B«, containing about 12 per cent, of alu-
minium and 3.75 per cent, of carbon. The crystals of this
compound are yellow and as brilliant as the diamond. Their
specific gravity is 2.6, hardness between that of corundum and
the diamond. They are not attacked by oxygen, even at a
high temperature; hot hydrochloric or sulphuric acid attacks
them only superficially, concentrated nitric acid dissolves them
slowly but completely. They resist boiling solution of caustic
potash or fused nitre, but take fire in fused caustic potash or
chromate of lead.
Aluminium and Carbon.
Deviile stated that he was unable to combine carbon with
aluminium. On decomposing carbon tetrachloride by aluniin-
ium, ordinary carbon was formed, while the aluminium remain-
ing was unchanged. The Cowles Company obtain in their
124 ALUMINIUM'.
electric furnace, when reducing a mixture of alumina and car-
bon alone, a yellow, crystalline substance which was exhibited
by Dr. T. Sterry Hunt,* as an alloy of aluminium and carbon,,
but that this is the case is not yet accepted as certain.
On dissolving impure aluminium in solution of caustic pot-
ash, a black residue was obtained which behaved, when filtered'
out and dried, partly like amorphous carbon. I have heard
it stated that molten aluminium does not dissolve appreciable-
quantities of carbon, and that its properties are affected con-
siderably thereby; but I am not able to give any further light
on the subject than the above experiment, which seemed to-
show considerable carbon in an impure metal. This is a sub-
ject which needs thorough investigation.
Since the observation just given was made, in 1890, the fact
that this residue does contain amorphous carbon has been es-
tablished by Le Verrier (see p. 57), who has also confirmed
Hunt's statements as to an aluminium carbide. Le Verrier
states I that up to his own experiments this compound was
unknown, but he must have been ignorant of Hunt's observa-
tions. The method used by Le Verrier was as follows: Little
boats of carbon were filled with aluminium, put into a carbon
tube through which a current of hydrogen was passed, and
heated in the electric furnace. After cooling, the aluminium
was of a grey color, and on breaking it was seen to be strewn
with brilliant fine-yellow crystals. To separate these out, the
aluminium is dissolved by concentrated hydrochloric acid, sur-
rounding the vessel with ice to keep the temperature low. The
residue is washed with ice-cold water. This whole operation
must be conducted as quickly as possible, since the carbide is
attacked by water.
The carbide thus prepared has a specific gravity, taken in
benzine, of 2.36. It is decomposed in the highest heat of an
electric furnace, attacked by chlorine at a red-heat, but only
♦Halifax Meeting, Am. Ins. Mining Engineers, Sept. i6, 1885.
tComptes Rendus, July, 1894, p. 16.
PROPERTIES OF ALUMINIUM COMPOUNDS. 125
superficially by oxygen, since the layer of alumina formed pro-
tects the part underneath. Violently attacked by sulphur at
that temperature, also by permanganate of potassium, bichro-
mate of potassium, chromic acid and oxide of lead ; potassium
chlorate has no action. Caustic potash in fusion attacks it very
energetically at about 300°. It slowly decomposes water in
the cold with a very curious result, namely, the formation of
jnethane gas, according to the reaction :
QAl^ + 12H2O = aCH, -f- 4A1(0H)3.
An analysis of these crystals gave the following result :
Aluminium. Carbon.
7448 23.5
7.5.12 24.2
74-7 24.7
74.9 24.8
75-7
(Required by the formula AI4C3.)
75.4 24.6
Aluminium Nitride.
Formula AIN, containing 66 per cent, of aluminium, is
iormed when aluminium is heated in a carbon crucible to a
high temperature. Mallet* obtained it unexpectedly when
heating aluminium with dry sodium carbonate at a high heat,
lor several hours, in a carbon crucible. The aluminium is par-
tially transformed into alumina, some sodium vaporizes, and
some carbon is deposited. After cooling, there are found on
the surface of the button little yellow crystals and amorphous
drops, to recover which the whole is treated with very dilute
hydrochloric acid. This product has the composition AIN.
"Calcined in the air it slowly loses nitrogen and forms alumina.
It decomposes in moist air, loses its transparency, becomes a
lighter yellow, and finally only alumina remains, the nitrogen
*Ann. der Chemie u. Pharmacie, 186, p. 155.
126 ALUMINIUM.
having formed ammonia. Melted with caustic potash it dis-
engages ammonia and forms potassium aluminate.
Aluminium Sulphate.
Anhydrous. — The salt obtained by drying hydrated alumin-
ium sulphate at a gentle heat has the formula Al2(S04)3, con-
taining 15.8 per cent, of aluminium, and of a specific gravity
of 2.67. By heating this salt several minutes over a Bunsen
burner it loses almost all its acid, leaving alumina. Hydrogen
likewise decomposes it at redness, forming water and sulphur
dioxide and leaving alumina with hardly a trace of acid.
Melted with sulphur, Violi states that it is transformed into
aluminium sulphide, evolving sulphurous acid gas.* Hot
hydrochloric acid in excess partly converts it into aluminium
chloride.
Hydrated. — This is the ordinary aluminium sulphate; its
formula is Al2(S04)3.i6H20, and it contains 8.0 per cent, of
aluminium, equal to 14.5 per cent, of alumina, and 47 per cent,
of water. The pure salt is not hygroscopic. In the presence
of impurities the amount of water increases to 18 H2O and the
salt becomes hygroscopic. It has a white, crystalline appear-
ance, and tastes like alum. It dissolves freely in water, from
which it crystallizes out at ordinary temperatures with the
above formula ; crystallized out at a low temperature it retains
27H2O, or one-half as much again. Water dissolves one-half
its weight of this salt, the solution reacting strongly acid ; it is
almost insoluble in alcohol. At a gentle heat it melts in its
water of crystallization, then puffs up and leaves a porous mass
of anhydrous sulphate which is soluble with difficulty in water.
If heated to redness it leaves only alumina. The salt with
16H2O has a specific gravity of 1.76; it is the salt found in
fibrous masses in solfataras, its mineralogical name being Halo-
trichite. A hydrated sulphate with 10H2O is formed and pre-
cipitated when alcohol is added to an aqueous solution of alu-
* Berichte der Deutschen Chemischen Gesellschaft, X, 293.
PROPERTIES OF ALUMINIUM COMPOUNDS. 12/
minium sulphate. On heating it acts similarly to the other
hydrated sulphates.
Basic. — On precipitating a solution of aluminium sulphate
with alkaline hydrate or carbonate, a series of basic salts are
formed. On precipitating with ammonia, the compound formed
has the formula AljO3.SO3.9HjO, corresponding to the mineral
Aluminite. If the ammonia is in insufficient quantity to en-
tirely precipitate the solution, a precipitate is very slowly
formed having the formula 3AI2O3.2SO3.20H2O. On precipitat-
ing a cold solution of alum by alkaline carbonate not in excess,
a precipitate is very slowly formed having the formula 2A1203.-
SO3.12H2O. If a very dilute solution of acetate of alumina is
precipitated by adding potassium sulphate, a compound de-
posits very slowly having the formula 2AI2O3.SO3.10H2O. Na-
tive minerals are met with of analogous composition to these
precipitates: Felsobanyte, 2AI2O3.SO3.10H2O ; Paraluminite,
2AI2O3.SO3.ISH2O. By heating a concentrated solution of alu-
minium sulphate with aluminium hydrate, and filtering cold,
the solution deposits on further cooling a gummy mass having
the formula Al203.2S03.;irH20. On washing with water it de-
posits a basic salt having the formula AI2O3.SO3. By letting
stand a very dilute solution of sulphuric acid completely satu-
rated with aluminium hydrate, Rammelsberg obtained trans-
parent crystals having the formula 3AI2O3.4SO3.30H2O. On
boiling a solution of aluminium sulphate with zinc, Debray
obtained a granular precipitate having the formula 5AI2O3.3SO3.-
20H2O. By leaving zinc a long time in a cold solution of alu-
minium sulphate, a gelatinous precipitate was obtained having
the formula 4AI2O3.3SO3.36H2O ; the same compound was
formed if the zinc was replaced by calcium carbonate.
The manufacture of aluminium sulphate from clay, aluminous
earths, cryolite, bauxite, etc. , is carried on industrially on a
very large scale ; descriptions of the processes used may be
found in any work on industrial chemistry — they are too foreign
to metallurgical purposes to be treated of here.
128 aluminium.
Alums.
Under this name are included a number of double salts con-
taining water, crystallizing in octahedra and having the general
formula R2S04.R2(S04)3.24H20, in which the first R may be
potassium, sodium, rubidium, caesum, ammonium, thallium or
even organic radicals ; the second R may be aluminium, iron,
manganese or chromium ; the acid may even be selenic, chro-
mic or manganic, instead of sulphuric. We will briefly describe
the most important alums consisting of double sulphates of
aluminium and another metal, remarking, as with aluminium
sulphate, that their preparation may be found at length in any
chemical treatise.
Potash Alum.
Formula K2S04.Al2(S04)3.24H20, containing 10.7 per cent, of
alumina or 5.7 per cent, of aluminium. Dissolves in 25 parts
of water at 0° and in two-sevenths part at 100°. The solution
reacts acid. It forms colorless, transparent octahedrons, insol-
uble in alcohol. On exposure to air they become opaque,
being covered with a white coating, which is said not to be
efflorescence — a loss of water — but to be caused by absorption
of ammonia from the air. The crystals melt in their water of
<;rystallization, but lose it all above 100°. Heated to redness
it swells up strongly, becomes porous and friable, giving the
product called calcined alum; at whiteness it loses a large part
of its sulphuric acid, leaving a residue of potassium sulphate and
alumina. If it is mixed with one-third its weight of carbon and
calcined, the residue inflames spontaneously in the air. If a
mixture of alumina and bisulphate of potassium is fused and
afterwards washed with warm water, a residue is obtained of
anhydrous alum, or K2S04.Al2(S04)3. The mineral Alunite is
a basic potash alum, K2S04.3(A1A-S0,).6H20.
Ammonia Alum.
Formula (NH0,SO4.Al2(SOl)s.24HjO, containing 11.3 per
■cent, of alumina or 6.0 per cent, of aluminium. Dissolves in
PROPERTIES OF ALUMINIUM COMPOUNDS. 1 29
20 parts of water at 0° and in one-fourth part at 100°. When
heated, the crystals swell up strongly, forming a porous mass,
losing at the same time water and sulphurous acid ; if the tem-
perature is high enough there remains a residue of pure alu-
mina. The temperature necessary for complete decomposition
is higher than that required for volatilizing ammonium sulphate
alone.
Soda Alum.
Formula Na2S04.Al2(S04)3.24H20, containing 11. i per cent,
of alumina or 5.9 per cent, of aluminium. Dissolves in an
equal weight of water at ordinary temperatures. The crystals
effloresce and fall to powder in the air. It is insoluble in abso-
lute alcohol. On account of its great solubility in water it
cannot be separated from ferrous sulphate by crystallization, and
therefore it is either contaminated with much iron or else, to
be obtained pure, special expensive methods must be adopted.
These diflSculties cause the manufacture of soda alum to be in-
significant in amount when compared with potash alum.
Aluminium-Metallic Sulphates.
Sulphate of aluminium forms double sulphates with iron,
manganese, magnesium and zinc, but these compounds are not
analogous to the alums. They are extremely soluble in water,
do not crystallize in octahedrons or any isometric forms, and
their composition is different from the alums in the amount of
water of crystallization. It has heen determined that the double
sulphates with manganese and zinc contain 25 equivalents of
water, which would permit their being considered as combina-
tions of sulphate of aluminium, Al2(S04)3.i8H20, with a sul-
phate of the magnesian series containing seven equivalents of
water, as ZnS04.7H20.
Aluminium Selenites.
By adding a solution of selenite of soda to one of sulphaite
of aluminium maintained in excess, an amorphous, voluminous
9
I30 ALUMINIUM.
precipitate forms, having the composition 4Al2O3.9SeO2.3H2O.
This substance decomposes on being heated, leaving alumina.
If varying quantities of selenious acid are added to this first
salt, other salts of the formulas Al2O3.3SeO2.7H2O, 2Al203.9Se02.
12H2O, Al2O3.6SeO2.SH2O, are formed. These are mostly in-
soluble in water and decompose on being heated, like the first.
Aluminium Nitrate.
Formula A1(N03)3.9H20 is obtained on dissolving aluminium
hydrate in nitric acid. If the solution is evaporated keeping it
strongly acid, it deposits on cooling voluminous crystals having
the formula 2Al(N03)3.isH20. This salt is deliquescent, melts
at 73° and gives a colorless liquid which, on cooling, becomes
crystalline. It is soluble in water, nitric acid, and alcohol ; on
evaporating these solutions it is obtained as a sticky mass. It
is easily decomposed by heat; if kept at 100° for a long time
it loses half its weight, leaving as residue a soluble salt of the
formula 2AI2O3.3N2O5.3H2O. Carried to 140°, this residue
loses all its nitric acid, leaving alumina. On this property is
based a separation of alumina from lime or magnesia, since the
nitrates of these latter bases resist the action of heat much
better than aluminium nitrate.
Aluminium Antimonate.
Al203.3Sb205.isH20 can be prepared by double decomposi-
tion from potassium antimonate and a soluble aluminium salt.
It deposits from solution after several days' standing in shin-
ing, microscopic crystals. At 100° it loses sHjO, at 150°, 2^
H2O more, at 200° it retains only 3H2O and becomes incandes-
cent. Al2O3.Sb2O5.9H2O has been also described.
Aluminium Phosphates.
The normal phosphate, AIPO4, is obtained as a white, gelat-
inous precipitate when a neutral aluminium solution is treated
with sodium phosphate. It is soluble in alkalies or mineral
acids, but not in acetic acid. If a solution of this salt in acids is
PROPERTIES OF ALUMINIUM COMPOUNDS. I3I
neutralized with ammonia, a basic phosphate is precipitated hav-
ing the composition 3Al,(OH)3PO,-|-2Al(OH)3. The mineral
Wavellite has this composition, with nine molecules of water.
The mineral Kalait contains AlP04+Al(OH)3+H20, and when
it is colored azure blue by a little copper it forms the Turquois.
Aluminium meta-phosphate has the formula AIP3O9 or AI2O3.-
3P.O,
Aluminium Carbonate.
If to a cold solution of alum a cold solution of sodium carbon-
ate is added drop by drop, stirring constantly until the solution
reacts feebly alkaline, a precipitate is obtained which, after be-
ing washed with cold water containing carbonic acid gas, con-
tains when damp single equivalents of alumina and carbonic
acid, ALjOa.COij. If the precautions indicated are not used, the
precipitate contains a very small proportion of carbonic acid.
Sestini * states that one litre of water saturated with carbonic
acid gas at the ordinary atmospheric pressure will dissolve 10
milligrammes of alumina, the solution becoming turbid on
boiling or agitation. This reaction is probably the key to the
understanding of the geological formation of native alumina
deposits.
When a solution of sodium bi-carbonate is added to one of
sodium aluminate, a double carbonate of the alkali and alumin-
ium is precipitated, which is easily soluble in acids. (Mende-
leefr.)
Aluminium Borate.
Formula 3AI2OS.BO3. Prepared by Ebelman by heating
together alumina, oxide of cadmium, and boric acid. After
three days' heating the platinum capsule containing the mix-
ture was found covered with transparent crystals of the above
composition, hard enough to scratch quartz and having a spe-
cific gravity of 3. Troost obtained the same substance by
heating alumina in the vapor of boron trichloride. Fremy pre-
pared it by heating fluoride of aluminium with boric acid.
* Gazetta Chim., Vol. 20, p. 313.
132 ALUMINIUM.
Ebelman also obtained it by heating a mixture of alumina and
borax to whiteness ; under these conditions crystals of corun-
dum were formed at the same time.
By precipitating a cold solution of alum with sodium borate,
double salts are obtained containing soda, but which leave on
washing with warm water two compounds having the formulae
zAlA-BOs.sH.O and 3Al203.2B03.8H,0. If the washing is
prolonged too far the two salts are completely decomposed,
leaving a residue of pure alumina.
Aluminium Silicates.
These compounds are very plentiful in nature, both hydrous
and anhydrous. The addition of a soluble aluminium salt to a
solution of sodium silicate would doubtless produce a precipi-
tate of aluminium silicate. Many of 'the native silicates have
been formed by the mingling of lime or alkaline water with
cabonated water carrying alumina in solution. In the native
silicates the silica and alumina occur in many proportions ;
the following ratios of alumina to silica have been observed :
2-1, 3-2, i-i, 2-3, 1-2, 1-3, 1-4, 1-8, thus varying from
tri-basic silicates to pent-acid silicates. The pure silicates
of aluminium alone are infusible before the blowpipe ; but
the presence of other elements, especially the alkalies, calcium
or iron, makes them quite easy to melt. Ordinary blast-
furnace slags are silicates of aluminium, calcium and magne-
sium, and vary from bi-acid to sesqui-basic silicates. In some
of these more basic silicates part of the aluminium present may
exert its acid character, and, in fact, the occurrence of crystals
of magnesium aluminate has been noted in crystallized blast-
furnace slag which was basic and rich in magnesium.
CHAPTER VI.
PREPARATION OF ALUMINIUM COMPOUNDS FOR REDUCTION.
We will consider this division under four heads : —
I. Alumina.
II. Aluminium chloride and aluminium-sodium chloride.
III. Aluminium fluoride and aluminium-sodium fluoride.
IV. Aluminium sulphide.
I.
The Preparation of Alumina.
We will treat this subject in three divisions : —
1 . From Aluminium Sulphate or Alums.
2. From Bauxite.
3. From CryoHte.
I. Preparation of Alumina from Alums or Aluminium
Sulphate.
Hydrated alumina can be precipitated from a solution of any
aluminium salt by ammonium hydrate, an excess of which re-
dissolves a portion. Its chemical formula is ordinarily written
AI2O3.3H2O or A^OHg). The aluminium hydrate thus pre-
cipitated is a pure white, very voluminous, almost pasty mass,
very hard to wash. By boiling and washing with boiUng water
it becomes more dense, but always remain very voluminous.
Washing on a filter with a suction apparatus gives the best re-
sults. At a freezing temperature this hydrate changes into a
dense powder which is more easily washed. On drying, it
shrinks very much in volume and forms dense, white pieces,
transparent on the edges. When dried at ordinary tempera-
tures it has the composition AljOg.H^O. On ignition, the
(133)
134 ALUMINIUM.
Other molecule of water is driven off, leaving anhydrous alu-
mina. After gentle ignition it remains highly hygroscopic, and
in a very short time will take up from the air 1 5 per cent, of
water. In this condition it is easily soluble in hydrochloric or
sulphuric acid. On stronger ignition it becomes harder and
soluble only with difficulty in concentrated acid ; after ignition
at a high temperature it is insoluble, and can only be brought
into solution again by powdering finely and fusing with potas-
sium acid-sulphate or alkaline carbonate. At ordinary furnace
temperatures alumina does not melt, but in the oxy- hydrogen
blow-pipe or the electric arc it fuses to a limpid Hquid and ap-
pears crystalline on cooling.
The precipitation in aqueous solution and subsequent ignition
is not economical enough to be practised on a large scale, and
for industrial purposes the aluminium sulphate or alum is ig-
nited directly. About the easiest way to proceed is to take
ammonia alum crystals, put them into a clean iron pan and
heat gently, when the salt melts in its water of crystallization.
When the water has evaporated, a brittle, shining, sticky mass
remains, which on further heating swells up and decomposes
into a dry, white powder. This is let cool, powdered, put into
a crucible and heated to bright redness. All the ammonia and
almost all the sulphuric acid are thus removed. The rest of
the acid can be removed by moistening the mass with a solu-
tion of sodium carbonate, drying and again igniting ; on wash-
ing with water the acid is removed as sodium sulphate. The
residue, however, will contain some caustic soda, which for its
further use in making aluminium chloride is not harmful. Pot-
ash alum can be treated in a similar way, the potassium sul-
phate being washed away after the first ignition. Still more
easily and cheaply can alumina be made by igniting a mixture
of 4 parts aluminium sulphate and i of sodium carbonate. On
washing, sodium sulphate is removed from the alumina.*
Deville used the following method at Javel : Ammonia alum or
* Kerl and Stohman, 4th Ed., p. 739.
PREPARATION OF ALUMINIUM COMPOUNDS. 135
even the impure commercial aluminium sulphate was calcined,
the residue appearing to be pure, white alumina, but it still con-
tained sulphuric acid, potassium sulphate, and a notable pro-
portion of iron. This alumina is very friable, and is passed
through a fine sieve, and put into an iron pot with twice its
weight of solution of caustic soda of 45 degrees. It is then
boiled and evaporated, and the alumina dissolves even though
it has been strongly calcined. The aluminate of soda produced
is taken up in a large quantity of water, and if it does not show
clear immediately, a little sulphuretted hydrogen is passed in,
which hastens the precipitation of the iron. The liquor is let
stand, the clear solution decanted ofT and subjected while still
warm to the action of a stream of carbonic acid gas. This con-
verts the soda into carbonate and precipitates the alumina in a
particularly dense form which collects in a space not one-
twentieth of the volume which would be taken up by gelatinous
alumina. This precipitate is best washed by decantation, but a
large number of washings are necessary to remove all the sodium
carbonate from it ; it is even well, before finishing the washing,
to add a little sal-ammoniac to the wash-water in order to hasten
the removal of the soda. The well-dried alumina is calcined at
a red heat.
Tilghman* decomposes commercial sulphate of alumina,
Al2(S04)3.i8H20, by filling a red-hot fire-clay cylinder with it.
This cylinder is lined inside with a magnesia fettUng, is kept at
a red heat, the sulphate put in in large lumps, and steam is
passed through the retort, carrying with it vapor of sodium
chloride. This last arrangement is effected by passing steam
into a cast-iron retort in which the salt named is kept melted,
and as the steam leaves this retort it carries vapor of the salt
with it. It is preferable, however, to make a paste of the sul-
phate of alumina and the sodium chloride, forming it into small
hollow cylinders, which are well dried, and then the fire-clay
cylinder filled with these. Then, the cylinder being heated to
* Mierzinski.
136 ALUMINIUM.
whiteness, highly superheated steam is passed over it. The
hydrochloric acid gas which is formed is caught in a condensing
apparatus, and there remains a mass of aluminate of soda,
which is moistened with water and treated with a current of
carbon dioxide and steam. By washing the mass, the soda
goes fnto solution and hydrated alumina remains, which is
washed well and is ready for use.
Mr. Webster's process for making pure alumina at a low price
was incorporated as a part of the Aluminium Co. Ld.'s pro-
cesses. The only description we can give of it is dated 1883.
* Three parts of potash alum are mixed with one part of
pitch, placed in a calcining furnace and heated to 200° or 250°.
About 40 per cent, of this water is thus driven off, leaving sul-
phate of potash and aluminium, with some ferric oxide. After
heating about three hours, the pasty mass is taken out, spread
on a stone floor, and when cold broken to pieces. Hydrochloric
acid (20 to 25 per cent.) is poured upon these pieces, placed
in piles, which are turned over from time to time. When the
evolution of sulphuretted hydrogen has stopped, about five per
cent, of charcoal-powder or lampblack, with enough water to
make a thick paste, is added. The mass is thoroughly broken
up and mixed in a mill, and then worked into balls of about a
pound each. These are bored through to facilitate drying, and
heated in a drying chamber at first to 40°, then in a furnace
from 95° to 150°. The balls are then kept for three hours at'
a low red heat in retorts, while a mixture of two parts steam
and one part air is passed through, so that the sulphur and car-
bon are converted into sulphurous oxide and carbonic oxide,
and thus escape. The current of gas carries over some potas-
sium sulphate, ferrous sulphate and alumina, and is therefore
passed through clay condensers.
The residue in the retorts consists of alumina and potassium
sulphate ; it is removed, ground to fine powder in a mill,
♦Austrian Patent, Sept. 28, 1882; English patent. No. 2580, 1881. Dingier, 1883,
vol. 259, p. 86.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 3/
treated with about seven times its weight of water, boiled in a
pan or boiler by means of steam for about one hour, then
allowed to stand till cool. The solution containing the potas-
sium sulphate is run ofifand evaporated to dryness, the alumina
is washed and dried. The potassium sulphate, as a by-product,
is said to pay one-half the cost of the process.
This deposit contains about 84 per cent, of alumina, while
that obtained by the old process of precipitation has only 65
per cent. Thus a large saving is effected in cost, and 19 per
cent, more alumina is obtained. In addition to this, the whole
of the by-products are recovered, consisting of potassium sul-
phate, sulphur (which is used in making sulphuric acid), and
aluminate of iron.
2. Preparation of Alumina from Bauxite.
At Salindres, the alumina used in the Deville process was
obtained from bauxite by the following processes, which are
in general use for extracting pure alumina from this mineral.
Bauxite is plentiful enough in the south of France, principally
in the departments of Herault, Bouches-du-Rhone, and Var.
It contains as much as seventy-five per cent, alumina. To
separate the alumina from ferric oxide, it is treated with car-
bonate of soda, under the influence of a sufiSciently high tem-
perature, the alumina displacing the carbonic acid and forming
an aluminate of soda, Al^Og.sNa^O, while the ferric oxide re-
mains unattacked. A simple washing with water then permits
the separation of the former from the insoluble ferric oxide.
The bauxite is first finely pulverized by means of a vertical
mill-stone, then intimately mixed with some sodium carbonate.
The mixture is made, for one operation, of —
480 kilos, bauxite.
300 " sodium carbonate of 90 alkali degrees.
This mixture is introduced into a reverberatory furnace, re-
sembling in form a soda furnace, and which will bear heating
138 ALUMINIUM.
Strongly. The mass is stirred from time to time, and it is kept
heated until all the carbonate has been attacked, which is
recognized by a test being taken which does not effervesce
with acids. The operation lasts from five to six hours.
The aluminate thus obtained is separated from ferric oxide by
a washing with warm water. This washing is made at first with
a feeble solution which has served for the complete exhaustion
of the preceding charge, which was last washed with pure
water, forming thus this feeble solution. This gives, on the
first leaching, solutions of aluminate concentrated enough to be
called strong liquor, which are next treated by the current of
carbonic acid gas to precipitate the hydrated alumina. The
charge is next washed with pure water, which completely re-
moves the aluminate ; this solution is the weak liquor, which is
put aside in a special tank, and used as the first leaching liquor
on the next charge treated. This treatment takes place in the
following apparatus (see Fig. i ) : ^ is a sheet-iron vessel, in
the middle of which is a metallic grating, F, on which is held
all round its edges, by pins, a cloth, serving as a filter. A
ought to be closed by a metallic lid held on firmly by bolts.
To work the apparatus, about 500 kilos of the charge to be
washed is placed on the filter cloth, the lid is closed, then
the steam-cock / of the reservoir A is opened. In A is the
weak solution from the last washing of the preceding charge.
The pressure of the steam makes it rise by the tube T into the
filter; another jet of steam, admitted by the cock b, rapidly
warms the feeble liquor as it soaks into the charge. After fil-
tering through, the strong liquor is drawn off by turning the
stop-cock G. The weak solution of the reservoir A is put into
the filter in successive portions, and not all at once ; and after
each addition of solution has filtered through, its strength in
B.° is taken, before any more solution is run in ; then, when the
solution marks 3° to 4°, it is placed in a special tank for weak
liquor, with all that comes through afterwards. Just about this
time, the weak liquor of the reservoir A is generally all used up,
and is replaced by pure water introduced by the tube d. All
PREPARATION OF ALUMINIUM COMPOUNDS.
139
the solutions which filtered through marking over 3° to 4° B.,
are put together, and form a strong liquor which marks about
12° B. This extraction of the aluminate being completed by
the pure water, the residue on the filter is taken out, and a new
operation may be commenced.
Fig. I.
B
bjc
u
-
Li— p
•<
V
G
r^
:
T
1
W
A
-iT
^
i-cvrrrpe O
The strong liquor is introduced into a vessel having an agi-
tator, where a strong current of carbonic acid gas may precipi-
tate the alumina from it. The gas is produced by small streams
of hydrochloric acid continuously falling on some limestone
contained in a series of earthenware jars. The precipitation
vessel is called a baratte. The carbonic acid after having
passed through a washing-flask, is directed to a battery of three
barattes, where the precipitation is worked methodically, so as
to precipitate completely the alumina of each baratte, and util-
I40
ALUMINIUM.
ize at the same time all the carbon dioxide produced. In order
to do this, the gas always enters first into a baratte in which
the precipitation is nearest completion, and arrives at last to
that in which the solution is freshest. When the gas is not all
absorbed in the last baratte, the first is emptied, for the precip-
itation in it is then completed, and it is made the last of the
series, the current being now directed first into the baratte
which was previously second, while the newly charged one is
made the last of the series. The process is thus kept on con-
tinuously. The apparatus used is shown in Fig. 2,
Fig. 2.
u. Charging pipe. b. Steam pipe. i. Steam drip. d. COj enters. / Discharge
pipe. A. Agitator, made of iron rods. C. Tank in which the precipitate settles.
B. Baratte body. D. Steam jacket.
Each baratte holds about 1200 litres of solution, and the
complete precipitation of all the alumina in it takes five to six
hours. A mechanical agitator stirs the contents continually,
and a current of steam is let into the double bottom so as to
PREPARATION OF ALUMINIUM COMPOUNDS. 141
keep the temperature of the solution about 70°. The precipi-
tated alumina and the solution of sodium carbonate which re-
main are received in a vat placed beneath each baratte. The
solution is decanted off clear, after standing, and then evapor-
ated down to dryness, regenerating the sodium carbonate used
in treating the bauxite to make the aluminate, less the inevit-
able losses inseparable from all industrial operations. The de-
posit of alumina contains considerable sodium carbonate me-
chanically intermixed, and is put into a conical strainer to
drain, or else into a centrifugal drying machine, which rapidly
drives out of the hydrated alumina most of the solution of
sodium carbonate which impregnates it ; a washing with pure
water in the drier itself terminates the preparation of the
alumina. At the works at Salindres, a part of this alumina is
converted into sulphate of alumina, which is sold, the remainder
being used for the aluminium manufacture. After washing in
the drier, the alumina presents this composition : —
Alumina 47.5
Water 50.0
Sodium carbonate 2.5
Behnke* produces alumina by igniting bauxite or a similar
mineral with sodium sulphate, carbon, and ferric oxide, using
for each equivalent of alumina present at least one equivalent
of alkali and one-half an equivalent of ferric oxide. The mix-
ture is heated in a muffle or reverberatory furnace. The fritted
product is ground, exposed to the air, and washed with water.
Sodium aluminate goes into solution along with some sodium
sulphate, while ferrous sulphide and undecomposed material
remains as a residue. By passing carbonic acid gas or gases
from combustion through the solution, the alumina is precip-
itated. The residue spoken of is roasted, the sulphurous oxide
given off utilized, and the residue used over in place of fresh
ferric oxide.
R. Lieber f proposes to treat bauxite, aluminous iron ore,
* German Patent (D. R. P.), No. 7256.
t German Patent (D. R. P.), No. 5670.
142 ALUMINIUM.
etc., in a somewhat similar way. These materials are to be
ground fine, mixed with sodium chloride and magnesium sul-
phate (Kieserite), moistened with water, and pressed into
bricks or balls. These are dried and put into a retort heated
red-hot by generator gas. Hydrochloric acid gas is first given
off, sodium sulphate and magnesium chloride being formed.
In a further stage of the process sulphurous oxide is evolved,
the alumina reacting on the sodium sulphate to form sodium
aluminate. The latter is washed out of the residue, and its
alumina precipitated by the ordinary methods.
H. Muller* proposes to extract the alumina from silicates
containing it by mixing them with limestone, dolomite, or
magnesite, also with alkali caustic, carbonate, or sulphate (in
the last case also with carbon), and heating the mixture to
bright-redness. Alkaline aluminate is washed out of the re-
sulting mass, while the residue, consisting of lime, magnesia,
iron oxide, etc., is mixed wifh water-glass and moulded into
artificial stone.
Common salt is said not to react on bauxite if fused with it
alone, but will decompose it if steam is used. Tilghmanf first
used this reaction in 1847. It is said that it was also used at
Nanterre and Salindres previously to 1865. A mixture of
sodium chloride and bauxite was treated in a closed retort and
steam passed through, or, better, in a reverberatory furnace an(J
steam passed over it, at a high temperature. Much sodium
chloride must have been lost by the latter arrangement. The
fused mass was treated with water, when sodium aluminate dis-
solved out.
R. WagnerJ proposed to make a solution of sodium sulphide,
by reducing sodium sulphate by carbon bisulphide, and to boil
the bauxite in it. The sulphuretted hydrogen evolved was to
be absorbed by ferric hydrate; while the sodium aluminate
* German Patent (D. R. P.), No. 12,947.
t Polytechnisches Journal, 106, p. 196.
J Wagner's Jahresb., 1865, p. 332.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 43
was converted into soda and alumina by any of the ordinary
methods.
Laur, a manufacturer of alumina in the south of France, has
attempted to use sodium sulphate instead of the carbonate, in
calcining bauxite. He finds it disadvantageous to exclude the
carbonate altogether, but uses for a bauxite containing 20 per
cent, of ferric oxide and 60 per cent, of alumina, about 66 of
sodium sulphate and 16 of sodium carbonate per 100 of baux-
ite. Carbon must also be mixed with the charge. Under
these conditions the ferric oxide present is first reduced to iron,
which finally becomes iron sulphide. The soda from both the
carbonate and the sulphate combines with the alumina to form
aluminate. An excess of soda is necessary to keep -the
aluminate in solution, and to keep the sulphide of iron out of
solution. The rest of the process is similar to that already de-
scribdti at Salindres.
According to Lowig's experiments, solution of sodium alumi-
nate can be precipitated by calcium, barium, strontium, or
magnesium hydrates, forming caustic soda and hydrated
alumina, the latter being precipitated, together with lime,
baryta, strontia, or magnesia. The precipitate is washed by
decantation, and then divided into two portions, one of which
is dissolved in hydrochloric acid, the other made into a mush
with water, and gradually added to the solution of the first half
until the filtrate shows only a very little alumina in solution.
Chloride of calcium, barium, strontium, or magnesium has been
formed, and the alumina all precipitated.
Dr. K. J. Bayer has made an improvement in the process of
extracting alumina from bauxite, which has received great
commendation from those directly interested in the business,
and who may be supposed to have proved its merits. Dr.
Bayer thus describes it : * Bauxite is fused with sodium car-
bonate or sulphate, and the solution obtained by washing,
containing sodium aluminate, is not decomposed by carbonic
* Stahl und Eisen, Feb. 1889, p. 112.
144 ALUMINIUM.
acid, as formerly, but by the addition of aluminium hydrate
with constant stirring. The decomposition of the solution goes
on until the quantity of alumina remaining in solution is to the
sodium protoxide as i to 6. This preciptation takes place in
the cold, and the pulverulent aluminium hydrate separted out
is easily soluble in acids. The alkaline solution remaining is
concentrated by evaporation, taken up by ground bauxite,
dried, calcined, and melted, and thus goes through the process
again. The use of this caustic soda solution containing alumina
is thus much more profitable than using soda, because by using
the latter only 75 per cent, of the bauxite used is utilized,
whereas by the former all th« alumina dissolved by the solution
is obtained again.
3. Preparation of Alumina from Cryolite.
By the Dry Way. — The following method was invented by
Julius Thomson ; the description is taken principally from Mier-
zinski's " Fabrikation des Aluminiums :" The cryolite is pulver-
ized, an easy operation, and to every lOO parts, 130 to 150
parts of chalk are added, and a suitable quantity of fluorspar
is also used, which remains in the residue on washing after ig-
nition. More chalk is used than is theoretically necessary, in
order to make the mass less fusible and keep it porous. But,
to avoid using too much chalk merely for this purpose, a cer-
tain quantity of coke may be put into the mixture. It is of the"
first importance that the mixture be very intimate and finely
pulverized. It is of greater importance that the mixture be
subjected to just the proper well-regulated temperature while
being calcined. The cryolite will melt very easily, but this is
to be avoided. On this account, the calcination cannot take
place in an ordinary smelting furnace, because, in spite of stir-
ring, the mass will melt at one place or another, while at an-
other part of the hearth it is not even decomposed, because
the heat at the fire-bridge is so much higher than at the farther
end of the hearth. Thomson constructed a furnace for this
special purpose (see Figs. 3 and 4), in which the flame from
PREPARATION OF ALUMINIUM COMPOUNDS.
1 45
the fire first went under the bed of the furnace, then over the
charge spread out on the bed, and finally into a flue over the
roof of the hearth. The hearth has an area of nearly 9 square
metres, being 4 metres long and 2.5 metres wide. It is charged
Fig. 3.
-V.L
twelve times each day, each time with 500 kilos of mixture,
thus roasting 6000 kilos daily, with a consumption of 800 kilos
of coal. The waste heat of the gases escaping from the furnace
Fig. 4.
<=J:
is utilized for drying the soda solution to its crystallizing point,
and the gases finally pass under an iron plate on which the
chalk is dried. In this furnace the mass is ignited thoroughly
without a bit of it melting, so that the residue can be fully
washed with water.
10
146 ALUMINIUM.
The decomposition takes place according to the formula —
2 (AlFs-sNaF) + 6CaC03=Al203.3Na20 + 6CaF, + 6C0„
the resultant product containing aluminate of soda, soluble in
water, and insoluble calcium flouride. The reaction com-
mences at a gentle heat, but is not completed until a red heat
is reached. Here is the critical point of the whole process,
since a very little raising of the temperature above a red heat
causes it to melt. However, it must not be understood that the
forming of lumps is altogether to be avoided. These lumps
would be very hard and unworkable when cold, but they can be
broken up easily while hot, so that they may be drawn out of
the furnace a few minutes before the rest of the charge is re-
moved, and broken up while still hot without any trouble.
The whole charge, on being taken out, is cooled and sieved, the
hard lumps which will not pass the sieve are ground in a mill
and again feebly ignited, when they will become porous and
may be easily ground up. However, the formation of these
lumps can be avoided by industrious stirring of the charge in
the furnace. A well-calcined mixture is porous, without dust
and without lumps which are too hard to be crushed between
the fingers. We would here remark that mechanical furnaces
of similar construction to those used in the manufacture of soda,
potash, sulphate of soda, etc., are more reliable and give the
best results if used for this calcination. The mixture, or ashes,
as the workmen call it, is drawn still hot, and washed while
warm in conical wooden boxes with double bottoms, or the box
may have but one bottom, with an iron plate about "]& milli-
metres above it. A series of such boxes, or a large apparatus
having several compartments, may be so arranged that the
washing is done methodically, i. e., the fresh water comes first
in contact with a residue which is already washed nearly clean,
and the fresh charge is washed by the strong liquor. This is
known as the " Lessiveur methodique," and an apparatus con-
structed especially for this purpose is described in Dingier 186,
376, by P. J. Havrez, but the subject is too general and the de-
PREPARATION OF ALUMINIUM COMPOUNDS. 1 4/
scription too long to be given here. A very suitable washing
apparatus is also the Buff-Dunlop, used in the soda industry
for washing crude soda, and described in Lunge's " Sulphuric
Acid and Alkali," Book II., p. 465. Since the ashes are
taken warm from the furnace the washing water need not be
previously heated, but the final wash-water must be warmed, as
the ashes have been cooled down by the previous washings.
As soon as the strong liquor does not possess a certain
strength, say 20° B., it is run over a fresh charge and so
brought up. The solution contains sodium aluminate.
The carbon dioxide necessary for precipitating the hydrated
alumina may be made in different ways. The gases coming
from the furnace in calcining the cryolite might be used if they
were not contaminated with dust; and there is also the diffi-
culty that exhausting the gases from the furnace would inter-
fere with the calcination. It has also been recommended to
use the gases from the fires under the evaporating pans, by
exhausting the air from the flues and purifying it by washing
with water. This can only be done where the pans are fired
with wood or gas. However, the lime-kiln is almost exclu-
sively used to furnish this gas. The kiln used is shaped like a
small blast furnace. Leading in at the boshes are two flues
from five fire-places built in the brickwork of the furnace, and
the heat from these calcines the limestone. The gases are
taken ofT by a cast-iron down-take at the top. At the bottom
of the furnace, corresponding with the tap hole in a blast fur-
nace, is an opening, kept closed, from which lime is withdrawn
at intervals. A strong blast is blown just above the entrance
of the side flues, and by keeping up a pressure in the furnace,
leakings into it may be avoided. The gas is sucked away from
the top by a pump, which forces it through a cleaning appar-
atus constructed like a wash-bottle, and it is then stored in a
gasometer. Instead of the pump, a steam aspirator may be
used, which is always cheaper and takes up less room.
The precipitation with carbonic acid gas is made by simply
forcing it through a tube into the liquid. The apparatus used
148 ALUMINIUM.
at Salindres is one of the most improved forms. (See p. 140.)
The precipitate is granular, and settles easily. However, it is
not pure hydrated alumina, but a compound of alumina, soda,
carbonic acid, and water, containing usually about —
Alumina ■ 45 per cent.
Sodium carbonate 20 "
Water 35 "
The sodium carbonate must be separated by long-continued
boiling with water, but by this treatment the alumina becomes
gelatinous and diflficult of further treatment. The precipitate
was formerly separated on linen filters, but centrifugal ma-
chines are now preferred. The evaporated solution gives a
high grade of carbonate of soda free from iron. The heavy
residue which is left after the ashes have been lixiviated con-
sists of calcium fluoride with small quantities of ferric oxide,
lime, undecomposed cryolite, and aluminate of soda, and has
not been utilized for any purpose.
R. Biederman* states that if steam is passed over molten
cryolite at a white heat, hydrofluoric acid gas and sodium
fluoride are formed and driven over, while a white, pure crys-
talline mass of alumina remains.
Utilization of aluminous fluoride slags. — At Nanterre, De-
ville used the following process for utilizing in one operation
the slags from the aluminium manufacture and the residues
from the sodium manufacture.
" The slags from making aluminium contain 60 per cent, of
sodium chloride and 40 per cent, of insoluble matter; the
former can be removed by a single washing. The insoluble
material is almost entirely aluminium fluoride, with a little
alumina and undecomposed cryolite. When fluorspar is used
as a flux, the sodium chloride in the slag is in part replaced by
calcium chloride ; but, in general, all the fluorine in the slag is
found combined with the aluminium, which shows the great
affinity between these two elements. The residues left in the
* Karl and Stohman, 4th Ed., p. 819.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 49
sodium retorts deteriorate quickly when exposed to the air, and
contain ordinarily, according to my analysis-^
Carbon 20.0
Carbonate of soda 14.5
Caustic soda 8,3
Sulphate of soda 2.4
Carbonates of lime and iron 29.8
Water 25.0
lOO.O
" To utilize these two materials, 5 to 6 parts of the sodium
residues are mixed carefully with one part of the washed slag,
and the whole calcined at a red heat. The fusion becomes
pasty ; it is cooled and washed, when aluminate of soda goes
into solution, and on treatment with carbon dioxide gives
sodium carbonate and alumina. According to my laboratory
experiments —
1000 grammes of sodium residues
160 " " washed slags
have given
no grammes of calcined alumina
225 " " dry sodium carbonate.
" The residue left on washing the fusion weighs about one-
half the weight of the soda residues used, and contains —
Carbon 30.0
Calcium fluoride 32.0
Alumina 0.6
Various other materials 37.4
" The latter item is formed of ferric oxide, oxide of man-
ganese, a little silica and some oxysulphide of calcium."
Decomposition of Cryolite in the Wet Way. — Deville used the
following method at Javel, which he thus describes; —
" In the Greenland cryolite there are to be found numerous
pieces containing siderite (ferrous carbonate). It is necessary
1 50 ALUMINIUM.
to extract all these pieces before using the mineral as a flux in
producing aluminium. The rejected fragments are then util-
ized by pulverizing them finely, mixing with about three-fourths
of their weight of pure, burnt lime and the whole carefully
slaked. After the slaking, water is added in large quantity,
and the material is heated in a large cast-iron vessel by means
of a steam-coil. A reaction takes place at once, and is com-
plete if the process is well conducted. Some insoluble alum-
inate of lime may be formed, but it can be recovered from the
residue by digesting itwith some solution of carbonate of soda.
The residue remaining is calcium fluoride, which settles easily,
and the clear liquor decanted off contains aluminate of soda,
from which alumina can be precipitated as before. The cal-
cined alumina obtained may contain iron when the cryolite
used contains a large amount of ferrous carbonate. It has ap-
peared to me that the latter mineral may be decomposed by
the lime, and some protoxide of iron be thus dissolved by the
soda in small quantity."
"We make alumina by this method at Nanterre only because
it utilizes the impure pieces of cryolite and works in conveni-
ently with the previously-described processes for utilizing the
slags."
An ingenious modification of the above process was devised
by Sauerwein. The first reaction is the same, five parts of
finely-powdered cryolite being boiled with four parts of burnt
lime, as free as possible from iron, producing a solution of
sodium aluminate and a residue of insoluble calcium fluoride.
Tissier recommended using two parts' of cryolite to one of lime,
but with these proportions only about one-third of the alumin-
ium in the cryolite is converted into soluble aluminate. Hahn
claims that complete decomposition takes place by using xoo
parts of cryolite to 88 parts of burnt lime. The solution is set-
tled, washed by decantation, and these washings put with the
strong solution first poured off; the next washings are reserved
for the fresh wash-water of another operation. The solution of
sodium aluminate is then boiled with a quantity of cryolite
PREPARATION OF ALUMINIUM COMPOUNDS. 151
equal to the amount first used, when sodium fluoride is formed
and alumina precipitated. This operation is in no way diffi-
cult, only requiring a little more attention than the first.
The alumina thus made is very finely divided. The reactions
involved are :
2(AlF3.3NaF) + 6CaO = AlA-sNa^O + 6CaF,.
2(AlFF3.3NaF) + AlA-sNa^O + 6H,0 = aCAlA-sH^O) + izNaF.
During the last operation it is best to add an excess of cryo-
lite, and keep the liquid in motion to prevent that mineral from
caking at the bottom. Lead is the best material to make these
precipitating tanks of, since iron would contaminate the alumina.
The precipitate is washed as in the previous operation. The
solution of sodium fluoride is boiled with the requisite quantity
of burnt lime, which converts it into caustic soda, NaOH, which
is separated from the precipitated calcium fluoride by decanta-
tion and washing.
In the establishment of Weber, at Copenhagen, where at one
time all the cryolite produced in Greenland was received, the
mineral was decomposed by acid. Hydrochloric acid attacks
the mineral slowly, but sulphuric acid immediately dissolves
the sodium fluoride, with disengagement of hydrofluoric acid ;
gelatinous aluminium fluoride separates out, and is attacked
more slowly. The cryolite requires nearly i ^ parts of sul-
phuric acid to dissolve it, the reaction being :
2(AlF3.3NaF) + 6H2SO4 = AlsCSO^s + 3Na,S04+ 12HF.
The solution is evaporated and crystallized, when the sodium
sulphate crystallizes out, and the mother liquid is treated for its
alumina. This method is too costly, when compared with more
recent processes, to be used at present.
According to Schuch* very finely-powdered cryoHte is dis-
solved by a large excess of hot dilute soda solution, but is
thrown down unaltered when carbonic acid gas is passed through
* Polytechnisches Journal, 165, p. 443.
152 ALUMINIUM.
the solution. An excess of concentrated soda liquor converts
the mineral into sodium aluminate and sodium fluoride, the for-
mer being soluble but the latter almost insoluble in the soda
solution.
II.
The Preparation of Aluminium Chloride and
Aluminium-Sodium Chloride.
Anhydrous aluminium chloride cannot be made by evap-
orating the solution of alumina in hydrochloric acid, for, as we
have seen, decomposition of the salt sets in, hydrochloric acid
is evolved and alumina remains. The same phenomena occur
on evaporating a solution of the double chloride. These anhy-
drous chlorides are prepared by a method discovered by
Oerstedt, applicable to producing a number of similar metallic
chlorides, which consists in passing a current of dry chlorine
gas over an ignited mixture of alumina and carbon.
Wohler* proceeded as follows in preparing the aluminium
chloride which was used in his early experiments : " Alumina is
mixed with charcoal powder and made plastic with oil. Cylin-
ders of about 5 millimetres diameter are made of this paste,
placed in a crucible with charcoal powder and heated until no
more combustible gases distil. After cooling the crucible the
cylinders are taken out, and a porcelain or glass tube open at
both ends filled with them. This is then placed in a combus-
tion furnace, connected at one end with a chlorine generator,
and at the other with a tubular extension from the further end
of which the gases escape, either into the air or into a flask
filled with milk of lime. When the whole apparatus is ready,
and filled with well-dried chlorine gas, the tube is heated to
glowing, when aluminium chloride is formed and condenses in
the extension of the tube."
Deville paid great attention' to the production and purifica-
*Pogg. Ann., n, p. 146.
PREPARATION OF ALUMINIUM COMPOUNDS.
153
tion of aluminium chloride ; the following is his account of the
processes used at Javel :
Manufacture on a Small Scale. — " I took 5 kilos of alumina
and mixed it with 2 kilos of carbon and a little oil ; the paste
was made into balls and ignited at a bright-red heat. The
compact, coke-like mass resulting was broken in pieces and
put, with its powder, into a stoneware retort, C (Fig. 5),
having a capacity of about 10 litres, and terminating in a neck.
Fig. s.
D. This retort was put in a furnace and heated to redness,
while a current of dry chlorine gas passed in by the tube A.
During the first few moments considerable quantities of water
vapor escape from the neck. When aluminium chloride distils,
as is shown by dense, white fumes, a porcelain or stoneware
funnel, E, is adjusted to the neck D, and kept in place by fill-
ing the joint with fine asbestos and then luting it over with a
little potter's clay mixed with hair. Against this funnel fits a
globular vessel, F, the joint being made tight in a similar way.
This apparatus condenses and holds all the chloride distilled.
However fast the chlorine may pass into the retort, it is so well
absorbed during three-fourths of the operation that not a trace
is mixed with the carbonic oxide escaping. However, the gas
always fumes a little, because of a small quantity of silicon
chloride being formed by the chlorine and carbon attacking the
sides of the retort, or from chloride of sulphur or a little chlor-
154 ALUMINIUM.
oxycarbonic acid. When the globe F is filled it is taken away
to extract the coherent, crystalline aluminium chloride it con-
tains, and is replaced immediately by another. During one
operation three jars were thus filled, and altogether a little over
lO kilos of chloride obtained. In the retort there remained
almost a kilo of coke mixed with alumina in the proportion of
two of carbon to one of alumina, making 330 grammes of the
latter remaining unattacked out of S kilos. This coke contains
also some double chloride of alumina and potassium and a little
calcium chloride, which render it deliquescent. This residue
was washed, mixed with a fresh quantity of alumina, and em-
ployed in a new operation."
Manufacture on a large scale. — " In applying this process on
a large scale, the oil and carbon were replaced by tar, the
alembic by a gas-retort, and the glass receiver by a small brick
chamber lined with glazed tiles. The alumina was obtained by
calcining ammonia alum in iron pots ; the residue obtained by
one calcination at a bright-red heat was mixed with pitch, to
which a little charcoal dust was added. The paste was well
mixed, introduced into iron pots, covered carefully and heated
until all vapors of tar ceased burning. The aluminous carbon
is used while it is still hot, if possible, as it is quite hygroscopic.
(This aluminous carbon conducts electricity wonderfully well ;
it is the best electrode to use in making aluminium by the bat-
tery, since its alumina regenerates the bath.) The residue is
hard, porous, and cracked, and contains sulphur from the sul-
phuric acid of the alum, a little iron, phosphoric acid in small
quantity, a perceptible proportion of lime, and finally potash,
which is always present in alums made from clay. The chlo-
rine gas used was conducted by lead pipes and passed over
calcium chloride before being used. The retort used was of
about 300 litres capacity, and was placed vertically in a sort of
chimney, C (Fig. 6), the flame circulating all around it. In
the bottom was a square opening, x, about 20 centimetres
square, which could be closed by a tile kept in place by a screw,
V. A porcelain tube pierced the sides of the furnace and en-
PREPARATION OF ALUMINIUM COMPOUNDS.
ISS
tered the retort at O; it was protected from the flame by a fire-
clay cyHnder inclosing it. At the top, the retort was closed by
a tile, Z, of refractory brick, in the centre of which was made
a square opening, W, oi \o \.o \2 centimetres side. Finally, an
opening, X, placed 30 centimetres below the plate Z, gave
issue to the vapors distilled, conducting them into the chamber
L. This condensation chamber was about i metre cube ; it had
Fig. 6.
one wall of bricks in common with the furnace, thus keeping
it rather hot. The other walls should be thin and set with
close joints and very little mortar. The cover, M, was mov-
able ; it and the sides of the chamber were of glazed tiles. An
opening 20-30 centimetres square in the lower part of the
chamber communicated with flues lined with lead, for a little
chloride was drawn into them. The uncondensed gas passed
to a chimney.
" To work such an apparatus it is necessary, first of all, to
dry it with the greatest care in all its parts, especially the con-
densation chamber. The retort is slowly heated and is left
156 ALUMINIUM.
Open at Z until it is judged quite dry, and is then filled with
red-hot, freshly-calcined mixture of carbon and alumina. The
top cover is then replaced, and the fire urged until the retort is
at a dark-red heat all over. Finally, chlorine is passed in, but
the opening at W is kept open ; the gas is allowed to pass into
the condensation chamber only when fumes of aluminium
chloride appear very abundantly at W. When the operation
proceeds right, almost all the aluminium chloride is found at-
tached in a dense, solid mass to the cover M. I have taken
out at one time a plate weighing almost 50 kilogrammes, which
was less than 10 centimetres thick; it was made up of a large
number of sulphur-yellow crystals penetrating each other and
looking like stalactites and long soda crystals. When it is
judged that the material in the retort is almost exhausted, the
hole X is opened, the residue scraped out, and fresh mixture
put in. During the operation there should be no white vapors
coming from the condensation chamber, but the odor of gas
will always be sharp because of the silicon chloride present,
formed unavoidably by the chlorine attacking the retort. A
gas retort, handled well, should last continuously two or three
months, or even more. The furnace should be constructed so
as to permit its easy replacement without much expense.
When in use, the retort is closely watched through spy-holes in
the wall, and any cracks which may appear promptly plastered
up, if not large, with a mixture of fine asbestos and soda
glass."
Purification of aluminium chloride. — " It often happens that
the chloride obtained is not pure, either from the nature of the
apparatus employed, or from neglect of the many precautions
which should be taken. In this case, to purify it, it is heated
in an earthen or cast-iron vessel with fine iron turnings. When
the hydrochloric acid, hydrogen and permanent gases are
driven from the apparatus, it is closed and heated hotter, which
produces a light pressure under which influence the aluminium
chloride melts and enters into direct contact with the iron.
The ferric chloride, which is as volatile as aluminium chloride.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 57
is transformed into ferrous chloride, which is much less volatile,
and the aluminium chloride can be obtained pure by being
volatilized away or distilled in an atmosphere of hydrogen."
When the processes just described were put in use at the
chemical works at La Glaciere, great care had to be taken to
avoid letting vapors and acid gases escape into the air, since
the works were surrounded by dwellings. To avoid these in-
conveniences, the vapor of aluminium chloride was made to
enter a heated space in which was sodium chloride, in order to
produce the less volatile double chloride; but the apparatus
choked up so persistently that the attempt was given up. It
then occurred to Deville to put sodium chloride into the mix-
ture itself in the retort. The same apparatus was used as be-
fore, except that the large gas-retort had to be replaced by a
smaller earthen one, which could be heated much hotter, the
grate being carried half way up the retort.* The condensation
chamber had to be replaced by a small earthen vessel. The
double chloride produced is fusible at about 200°, and is quite
colorless when pure, but colored yellow by iron. It is, more-
over, very little altered in dry air when in compact masses, and
can be easily handled. When the double chloride is obtained
quite pure, it gives up its aluminium completely when reduced
by sodium.
The following description by M. Margottetf will show the
form of apparatus used in 1882 by the French company carry-
ing on the Deville process at Salindres : —
The double chloride may be obtained in the same manner as
the simple chloride ; it is sufficient to put some common salt,
NaCl, into a mixture of alumina and carbon, and on heating
this mixture strongly there is formed, by the action of the
chlorine, aluminium-sodium chloride, which distils at a red heat
and condenses in a crystalline mass at about 200°. The hy-
* It was when first using this process that Deville borrowed some zinc retorts from
the Vielle Montagne works, and since they contained a little zinc in their composition
the aluminium made for a while was quite zinciferous.
t Fremy's Ency. Chimique.
158
ALUMINIUM.
drated alumina obtained in the preceding operation is mixed
witli salt and finely pulverized charcoal, in proper proportions,
the whole is sifted, and a mixture produced as homogeneous
as possible ; then it is agglomerated with water and made into
balls the size of the fist. These balls are first dried in a drying
stove, at about 150°, then calcined at redness in retorts, where
the double chloride should commence to be produced just as
the balls are completely dried. These retorts are vertical cyl-
inders of refractory earth ; each one is furnished with a tube in
its lower part for the introduction of chlorine, and with another
towards its upper end for the exit of the vapor of double chlo-
ride (see Fig. 7). A lid carefully luted during the operation
Fig. 7.
with a mixture of fine clay and horse-dung serves for the charg-
ing and discharging of the retort. The double chloride is con-
densed in earthen pots like flower-pots, made of ordinary clay,
and closed by a well-luted cover, into which passes a pipe of
clay to conduct the gas resulting from the operation into flues
connected with the main chimney. Each retort is heated by a
fire, the flame of which circulates all round it, and permits
keeping it at a bright red heat. An operation is conducted as
follows : The retort is filled with stove-dried balls, the lid is
PREPARATION OF ALUMINIUM COMPOUNDS. 1 59
carefully luted, and the retort is heated gently till all the mois-
ture is driven off. This complete desiccation is of great im-
portance, and requires much time. Then chlorine, furnished
by a battery of three generating vessels, is passed in. During
the first hours, the gas is totally absorbed by the balls ; the
double chloride distils regularly for about three hours, and runs
into the earthen pots, where it solidifies. Toward the end, the
distillation is more difficult and less regular, and the chlorine is
then only incompletely absorbed. After each operation there
remains a little residue in the retort, which accumulates and is
removed every two days, when two operations are made per
day. One operation lasts at least twelve hours, and a retort
lasts sometimes a month. The double chloride is kept in the
pots in which it was condensed until the time it is to be used
in the next operation ; it is almost chemically pure, save traces
of iron, and is easy to keep and handle.
The following estimate was made by Wurtz, in 1872, show-
ing the cost of a kilo of aluminium-sodium chloride as made
by the above process: —
Anhydrous alumina 0.59 kilos @ 86 fr. per 100 kilos = o it. 50.7 cent.
Manganese dioxide 3.74 " " 14 " " " " = o " 52.3 "
Hydrochloric acid 15.72 " " 3" " " " =0" 47.1 "
Coal 25.78 " " 1.40 ' =0" 36.1 "
Wages o" 23.8 "
Expenses o " 38.0 "
Total 2 fr. 48.0 cent.
This is equal to about 22^ cents per pound. An average
of 10 kilos of this was used to produce one kilo of aluminium,
which shows a yield of only 70 per cent, of the contained alu-
minium, and an increased cost of 6y cents on every pound of
aluminium from the imperfection of reduction. In this respect
there certainly seems large room for improvement.
The largest plant ever erected for the manufacture of alu-
minium-sodium chloride was that of the Aluminium Co. Ltd.,
at Oldbury, near Birmingham, England. The plant was com-
menced in the latter part of 1887, and was in working order in
l6o ALUMINIUM.
July, 1888. The process is in principle indentical with that used
at Salindres, but the whole was on such a large scale that the
description is still interesting.
Twelve large regenerative gas furnaces are used, in each of
which are placed five horizontal fire-clay retorts about 10 feet
in length, into which the mixture is placed. These furnaces are
in two rows, of six each, along each side of a building about
250 feet long, leaving a clear passage down the centre 50 feet
wide. Above this central passage is a platform swung from
the roof, which carries the large lead mains to supply chlorine
to the retorts ; opposite each retort is a branch pipe controlled
by a valve. The valves are designed so that the chlorine must
pass through a certain depth of (non-aqueous) liquid, thus
regulating the flow and preventing any back pressure in the re-
tort from forcing vapor into the main. The opposite or back
ends of the retorts are fitted with pipes which convey the vapor
of the double chloride into cast-iron condensers and thence into
brick chests or boxes, the outsides or ends of which are closed
by wooden doors fitting tightly. Convenient openings are ar-
ranged for clearing out the passages, which may become
choked because of the quickness with which the double chlor-
ide condenses. On looking down the centre of the building it
presents the appearance of a double bank of gas retorts for
making ordinary illuminating gas, except that the retorts are
only one-high. (Fig. 8).
The chlorine plant is on a correspondingly large scale, the
usual manganese-dioxide method being employed and the spent
liquor regenerated by Weldon's process. The chlorine gas is
stored in large gasometers from which it is supplied to the re-
torts at a certain pressure. The mixture for treatment is made
by mixing hydrated alumina with common salt and carbon in
the form of charcoal powder or lamp-black. This being well
mixed is moistened with water, thrown into a pug-mill from
which it is forced out as solid cylinders, and cut into about 3
inch lengths by a workman. The lumps are then piled on top
of the large chloride furnaces to dry. In a few hours they are
PREPARATION OF ALUMINIUM COMPOUNDS.
I6I
hard enough to allow handling, and are put into large wagons
and wheeled to the front of the retorts.
When the retorts are at the proper temperature for charging,
the balls are thrown in until the retort is quite full, the fronts
are then put up and luted tightly with clay, and the charge left
alone for about four hours, during which the water of the hy-
drated alumina is completely expelled, the rear end of the re-
tort being disconnected from the condensing chamber, which
Fig. 8.
must be kept perfectly dry, and connected directly with the
chimney. At the end of this time the chlorine is turned on
and the retort connected with the receiver. At first the chlo-
rine passed in is all absorbed by the charge and only carbonic
oxide escapes into the boxes, where it is ignited and burns,
thus warming them up. After a certain time dense fumes are
evolved, and then the condensers are shut tightly and the un-
condensed gases pass into the chimney. The chlorine is passed
in for 72 hours in varying quantity, the boxes at the rear being
opened from time to time by the workmen to note the pro-
gress of the distillation. The greater part of the double chlo-
II
1 62 ALUMINIUM.
ride liquefies and trfckles down to the floor of the chambers,
but a portion sublimes and condenses on the walls as a yellow
crystalline powder. These chambers are emptied from time to
time and the contents packed away in air-tight wooden chests,
that it may keep without absorbing moisture from the air. At
the end of the distillation the chlorine valves are closed and
the condenser boxes cleaned out ; the retorts are also opened
at their front end and the residue raked out. This residue
consists of a small quantity of alumina, charcoal and salt, and
is remixed in certain proportions with fresh material and used
over again. The retorts are then immediately re-charged and
the operations repeated. Each set of five retorts produces
about 1600 to 1800 lbs. in one operation, or say 3500 lbs. per
week. The twelve furnaces are therefore capable of producing
easily 1,500,000 lbs. of double chloride per annum. Since 10
lbs. of this salt are required to produce i lb. of aluminium, the
capacity of the works is thus seen to be 150,000 lbs. or over of
metal per year.
This last remark as to the proportion of chloride required to
form the metal will show the absolute necessity there is to keep
iron from contaminating the salt. This gets in, in varying pro-
portions, from the iron in the materials used and in the fire-clay
composing the retort, and exists as ferrous and ferric chlorides.
Exercising the utmost care as to the purity of the alumina and
charcoal used, and after having the retorts made of a special
fire-clay containing a very small percentage of iron, it was found
impossible to produce a chloride on a large scale containing less
than 0.3 per cent, of iron. This crude chloride is highly de-
liquescent and varies in color from light yellow to dark red —
the color depending not so much on the absolute amount of
iron present as on the proportion of iron present as ferric salt,
which has a high color. Since practically all the iron present
in the salt passes into the aluminium, it is seen that the latter
would contain 3 per cent, or more of iron. For some time the
only way to obviate this difficulty was to resort to purifying the
aluminium, by which the content of iron was finally reduced to
PREPARATION OF ALUMINIUM COMPOUNDS. 1 63
2 per cent. Mr. Castner has since perfected a process for
purifying the double chloride by which only o.oi per cent, of
iron is left in it. The principle employed in doing this is de-
scribed in the patent claims* to be the reduction of the iron salts
to metallic iron by melting the chloride (single or double) with
a quantity of metallic aluminium or sodium sufiScient for this
purpose. The purified chloride is quite white and far less de-
liquescent than the crude salt, which seems to indicate that the
iron chlorides have a large share in rendering the crude salt so
deHquescent. The purified chloride is preserved by melting
and running into tight iron drums. A process of purification
used later by Mr. Castnerf consisted in separating out the iron
electrolytically. The melted salt was passed slowly along a
trough on the sides of which were electrodes kept at a tension
sufficient to decompose the iron chlorides, the tension also
being gradually decreased from one end to the other propor-
tionally to the decreasing quantity of iron in the material as it
passed along.
The success of the manufacture of the double chloride is said
to depend on the proportions of the mixture, the temperature
of the furnace, the quantity of chlorine introduced, and the de-
tails of construction of the retorts ; but very little information
on these points has been made public. The following figures
may give some idea of the quantities of materials used : The
production of 1000 lbs. of double chloride is said to require —
Common salt 357 lbs.
Hydrated alumina 491 "
Chlorine gas 674 "
Coal 1800 "
The salt and hydrated alumina are therefore mixed in about
the same proportion as those indicated by the formula which
represents the reaction
*U. S. Patent, No. 409,668, Aug. 27, 1889.
tU. S. Patent, No. 422,500, March 4, 1890.
1 64 ALUMINIUM.
Al,C3+2NaCl+3C+6Cl=Al,Cl6.2NaCl+3CO.
for if we assume the hydrated alumina used to contain 90 per
cent, of that compound, the 491 lbs. of it used would corres-
pond to very nearly the amount of salt said to be used. As
to the cost of this double chloride, so many uncertain elements
enter into it that it cannot be satisfactorily estimated from the
data at hand. We are informed, however,* that the double
chloride used represented 43 per cent, of the cost of aluminium
to this company. If we place the total cost at 8 shillings per
lb. this would indicate a trifle over 4 pence per lb. as the cost
of the double chloride. It was probably not over 3 pence.
H. A. Gadsden,! of London, patented a method of obtaining
aluminium, in which the aluminium chloride used is obtained by
a method similar in all respects to the process as described by
Deville, except that the corundum or bauxite used is mixed
with about 10 per cent, of sodium or potassium fluoride and a
small quantity of fluorspar. After this has been mixed and
calcined it is pulverized, 10 per cent, of charcoal dust added,
made into balls and heated in a muffle until pasty. Taken
out of the muffle they are then put into a retort, heated highly,
and chlorine gas passed over them, when aluminium chloride
distils.
Count R. de Montgelas| patents a process for producing
aluminium chloride and the double chloride with sodium, in •
which the only difference from the preceding methods is that
molasses is used instead of pitch for moulding the mixture into
balls, the mixture otherwise containing alumina, charcoal, and
sodium chloride ; and it is claimed that by regulating the heat
at which chlorine is passed over this mixture, previously cal-
cined, aluminium chloride can be volatilized while aluminium-
sodium chloride remains in the retort. The use of horizontal
retorts is recommended.
*Zeitschrift des Verein Deutscher Ingenieure, 1889, p. 301.
t German Patent (D. R. P.) No. 27,572 (1884).
I English Patents Nos. 10,011, 10,012, 10,013, Aug. 4, 1886.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 65
Prof. Chas. F. Mabery,* of the Case School of Applied Sci-
ence, Cleveland, patented and assigned to the Cowles Bros, the
process of making aluminium chloride, consisting in passing
dry chlorine or hydrochloric acid gas over an alloy of alumin-
ium and some other metal kept in a closed vessel at a temper-
ature sufficient to volatilize the aluminium chloride formed,
which is caught in a condenser. Or, hydrochloric acid gas is
passed through an electrically heated furnace, in which alumina
is being decomposed by carbon, a condenser being attached to
the opposite end of the furnace.
Mr. Paul Curiej states that aluminium chloride can be made
by passing vapors of carbon disulphide and hydrochloric acid
either simultaneously or successively over ignited alumina or
clay. The first forms aluminium sulphide, which the latter
converts into the volatile chloride, which distils.
H. W. WarrenI recommends the following process as of gen-
eral application in producing anhydrous metallic chlorides.
Petroleum is saturated with either chlorine or hydrochloric acid
gas, both gases being soluble in it to a large extent, particu-
larly the latter gas. This operation is performed at a low tem-
perature, as more of the gases is then dissolved. The oxide of
the metal, alumina, for instance, is put into large earthenware
retorts, and raised to red heat. The saturated oil is then boiled
and its vapor passed into the retort. On contact with the
oxide a strong reaction commences, fumes of aluminium chlor-
ide are at once evolved, and distil into a condenser, the opera-
tion being continued until no more white fumes appear. Then
fresh alumina is supplied, and the reaction continues. The
aluminium chloride may be purified from any oil by gentle ap-
plication of heat. Mr. Warren also used naphthaline chloride
with advantage, as also chloride of carbon, but their high price
rendered them unable to compare with petroleum in economy.
* U. S. Patent, Oct. 26, 1886.
t Chemical News, 1873, p. 307.
J Chemical News, April 29, 1887.
1 66 ALUMINIUM.
Aluminium bromide can be similarly prepared by substituting
bromine for chlorine.
Camille A. Faure, of New York, the well-known inventor of
the Faure storage battery, has patented* a process for produc-
ing aluminium chloride, which is very similar to the above
method. The manipulation is described as follows : An oxy-
genated ore of aluminium is brought to about a red heat by
bringing it, in a furnace, into direct contact with the flame.
When at proper heat the flame is cut off and a gas containing
carbon and chlorine introduced. A mixture of petroleum vapor
or a similar hydrocarbon with hydrochloric acid gas is pre-
ferred. Vaporized chloride of aluminium immediately passes
off into a condenser.
In a paper written by Mr. Faure, and read before the French
Academy of Sciences by M. Berthelot,t it was stated that the
aim of this process was to suppress the prominent disadvant-
ages of the older methods : viz., cost and wear and tear of re-
torts, great consumption of fuel, slowness of the operation,
large amount of labor, and cost of the chlorine. For this pur-
pose the chlorine is replaced by hydrochloric acid gas and the
carbon by a hydrocarbon. Since all pure hydrocarbons are
decomposed at a red heat with deposition of carbon, the pro-
cess would appear impracticable ; but a proper mixture of hy-
drochloric acid gas and naphthaline vapor is said not to de-
compose by the highest temperature alone, a new compound
being formed, a sort of napthaline chloride, which is exceed-
ingly corrosive and powerful enough to attack any oxide and
convert it into chloride. To carry out the process a gas fur-
nace with large bed is used. On this is spread a layer of small
pieces of bauxite about two feet deep. The flame comes in
over the ore, passes downward through it and through numer-
ous holes arranged in the hearth, and thence to a chimney. In
this way the heat of the gases is well utilized, while the layer
* U. S. Patent, No. 385,345, July 3, 1888.
t July 30, 1888.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 67
of bauxite is heated to whiteness on top and to low-red at the
bottom. The flames are then turned off and the mixture of
naphthaHne and hydrochloric acid vapors passed upward
through the bed, and by their reaction producing aluminium
chloride, which is diverted by suitable flues into a condenser.
It is claimed that by careful fractional condensation the chlor-
ides of silicon, iron, calcium, etc., formed from impurities in
the bauxite, can be easily separated, that of silicon being
more volatile and those of iron and calcium less volatile than
aluminium chloride. As naphthaline is a bye-product from
gas-works, it is claimed that it can be bought for i ^ cents per
lb., and that only j^ oi a lb. is used per lb. of aluminium chlo-
ride produced. It is also claimed that one furnace, with two
men to work it, will produce 4000 lbs. of chloride a day. The
estimated cost of the chloride is about i }4 cents per pound, of
which 17 per cent, is for beauxite, 47 per cent, for hydrochloric
acid, 27 per cent, for naphthaline, and 9 per cent, for labor.
Mr. Faure experimented in the vicinity of New York during
1889, and was sanguine of having the process at work in 1890,
but no commercial process has resulted from these efforts.
(See further. Chap. XI.)
In all the processes for producing aluminium chloride so far
considered, the use of common clay was not recommended,
since silicon chloride is formed as well as aluminium chloride.
The only method proposed for using clay for this purpose is
that of M. Dullo, nearly twenty years ago, and which cannot
have been very successful, since it has not been heard of in
operation. We will repeat his remarks, however, for there is
still a large field open in the utilization of clay for the manu-
facture of aluminium, and since the metal is becoming so cheap
the manufacturers are not above looking for and utilizing the
cheapest raw material available.
* " Aluminium chloride may be obtained easily by direct
treatment of clay. For this purpose a good clay, free from iron
and sand, is mixed with enough water to make a thick pulp,
* Bull, de la Soc. Chem., i860, vol. v., p. 472.
1 68 ALUMINIUM.
to which are added sodium chloride and pulverized carbon.
For every lOO parts of dry clay there are taken I20 parts of
salt and 30 of carbon. The mixture is dried and broken up
into small fragments, which are then introduced into a red-hot
retort traversed by a current of chlorine. Carbonic oxide is
disengaged, while at the same time aluminium chloride and a
little silicon chloride are formed. It is not necessary that the
chlorine should be absolutely dry, it may be employed just as
it comes from the generator. The gas is absorbed very rapidly,
because between the aluminium and silicon there are reciprocal
actions under the influence of which the chemical actions are
more prompt and energetic. The aluminium having for chlo-
rine a greater afifinity than silicon has, aluminium chloride is
first formed, and it is only when all the aluminium is thus trans-
formed that any silicon chloride is formed. When the latter
begins to form the operation is stopped, the incandescent mix-
ture is taken out of the retort and treated with water. The
solution is evaporated to dryness to separate out a small quan-
tity of silica which is in it, the residue is taken up with water,
and aluminium-sodium double chloride remains when the
filtered solution is evaporated to dryness."
We must say of M. Dullo's suggestions that it is the general
experience that the more volatile silicon chloride is formed
first; it is also very improbable that a solution of aluminium-
sodium chloride can be evaporated without decomposition.
III.
The Preparation of Aluminium Fluoride and
Aluminium-Sodium Fluoride (Cryolite).
Natural cryolite is too impure for use in many operations
which aim to produce very pure aluminium. Schuh has pro-
posed boiling the mineral in solution of soda. Under certain
conditions sodium aluminate is formed (see p. JJI), but if the
solution of soda is dilute the liquor remains clear after taking
up the cryolite, and on passing a current of carbonic acid gas
PREPARATION OF ALUMINIUM COMPOUNDS. 1 69
through it aluminium-sodium fluoride is precipitated. In this
way the pure double fluoride can be separated from impure
cryolite.
Berzelius recommended preparing artificial cryolite by de-
composing aluminium hydrate by a solution of sodium fluoride
and hydrofluoric acid, the hydrate being added to the liquid
until its acidity was just neutralized : —
A1,03.3H,0 + 6NaF + 6HF = 2(AlF3.3NaF) + 6H,0.
Deville states that on adding sodium chloride to a solution
obtained by dissolving alumina in an excess of hydrofluoric
acid, a precipitate of cryolite is obtained. Since cryolite is
hardly attacked at all by hydrochloric acid, it is probable that
the reaction occurring is
AIF3 + 3HF + sNaCl = AlFa.sNaF + 3HCI.
The process which Deville recommended as best, however, is
the treatment of a mixture of calcined alumina and carbonate
of soda, mixed in the proportions in which their bases exist in
cryolite, by an excess of pure hydrofluoric acid : —
AliiOa -I- sNa/'Os + i2HF=2(AlF.3NaF) -|- 3CO2 + 6H2O.
100 parts of pure alumina requiring 310 parts of sodiurri car-
bonate and 245 of anhydrous hydrofluoric acid, there being
410 parts of cryolite formed. On drying the mass and melting
it there results a limpid, homogeneous bath having all the
characteristics of cryolite, being reduced by sodium or by an
electric current, which would not result from a mere mixture ot
alumina and sodium fluoride melted together.
Deville also states that when anhydrous aluminium chloride
is heated with sodium fluoride in excess, a molten bath results
of great fluidity, and on cooling and dissolving away the excess
of sodium fluoride by repeated washings the residue is similar
to cryolite, while the solutions contain no trace of any soluble
aluminium salt: —
AICI3 + 6NaF=AlF3.3NaF 4- sNaCl.
I/O ALUMINIUM.
It is evident, however, that the above reaction would be the
reverse of a profitable one, and is therefore not of economical
utility.
Pieper* patents a very similar reaction, but operates in the
wet way. A solution of aluminium chloride is decomposed by
adding to it a suitable quantity of sodium fluoride in solution.
Sodium chloride is formed and cryolite precipitated, as in the
last reaction given. By adding different proportions of sodium
fluoride solution, precipitates of double salts are obtained, con-
taining varying proportions of the two fluorides. The use of
aluminium chloride in solution would dispense with the objec-
tion made to Deville's analogous method, and this process
would very probably produce cryolite quite cheaply.
Brunerf produced aluminium fluoride by passing hydro-
fluoric acid gas in the required quantity over alumina heated
red hot in a platinum crucible: —
Al20, + 6HF=2A1F3 4 3H2O.
Devillef states that it can be made by melting together the
equivalent quantities of cryolite and aluminium sulphate :
2(AlF3.3NaF) -I- Al,(S04)3.:eH,0 = 4AIF3 + sNa^SO^ + ;i;H.,0.
On washing the fusion, sodium sulphate goes into the solu-
tion. It is also stated that hydrochloric acid gas acting on a
mixture of fluorspar and alumina at a high temperature will
produce aluminium fluoride :
AlA + sCaF^ + 6HC1 = 2AIF3 4- aCaCl, -1- 3H.,0.
The calcium chloride would be partly volatilized and the re-
mainder washed out of the fusion.
Hautefeuille§ obtained crystallized aluminium fluoride by
♦German Patent (D. R. P.), No. 35,212.
t Pogg- Annalen, 98, p. 488.
t Ann. de. Chim. et de Phys. [3], 61, p. 333; [3], 49, p. 79.
§Idem, [4], 4.P- iS3-
PREPARATION OF ALUMINIUM COMPOUNDS. 17I
passing hydrofluoric acid gas and steam together over red-hot
alumina.
Ludwig Grabau, of Hanover, bases his process of producing
aluminium on the reduction of aluminium fluoride (see Chap.
X.), which is prepared on a commercial scale by the following
ingenious methods :
* The process is based on the conversion of aluminium sul-
phate into fluoride by reaction with cryolite, the fluoride being
afterward reduced by sodium in such a manner that a double
fluoride of sodiuni and aluminium results, which is used over
again, thus forming a continuous process. The purest obtain-
able cryolite is used to start the process, after which no more
is needed, the material supplying the aluminium being its sul-
phate, which can be obtained cheaply in large quantities, and
almost perfectly pure. The process is outlined by the reac-
tions—
2 (AlFa-sNaF) + AUCSO*), = 4AIF3 + sNa.SO^
2AIF3 + sNa = AH AlFs.sNaF.
It is thus seen that theoretically the cryolite would be exactly
reproduced, but the losses and incomplete reactions unavoida-
ble in practice would cause less to be obtained, and necessitate
the continual addition of fresh cryolite ; since, however, it is
not desired to base the process on the continual use of cryo-
lite, because of the impurities in that mineral, an indirect pro-
cess is used, consisting of two reactions, in place of the first
given above, in which theoretically a larger quantity of cryolite
is finally obtained than is used to begin with. This is operated
by introducing fluorspar into the process, the base of which
goes out as calcium sulphate or gypsum, and so supplies the
fluorine needed.
In practice, a solution of aluminium sulphate is heated with
powdered fluorspar (obtained as pure as possible and further
cleaned by treatment with dilute hydrochloric acid). The
♦German Patent (D. R. P.), No. 48,535. March 8, 1889.
172 ALUMINIUM.
aluminium sulphate will not be entirely converted into fluoride,
as has been previously observed by Friedel,* but about two-
thirds of the sulphuric acid is replaced by fluorine, forming a
fluorsulphate of aluminium. This latter compound remains in
solution, while gypsum and undecomposed fluorspar remain as
a residue and are filtered out.
AlaCSO,)^-!- 2CaF, = Al^F.CSOi) +2 CaSOi.
This solution is concentrated and mixed with cryolite in such
proportion that the alkali in the latter is just equivalent to the
sulphuric acid in the fluor-sulphate. The mass is dried and
gnited, and the product washed and dried.
3AUF,(S0,) + 2(AlF3.3NaF) =8A1F3+ 3Na,S04.
On reduction with sodium, the 8 molecules of aluminium fluor-
ide, treated with sodium as by the reaction given, produce 4
molecules of the double fluoride. It is thus seen that after
allowing for reasonable losses in the process there is much .
more cryolite produced than is used, and the excess can be
very profitably sold as pure cryolite, being absolutely free from
iron or silica.
Grabau proposed to obtain his aluminium sulphate solution
directly from kaolin, by treatment with sulphuric acid, and thus
utilize this most abundant of the aluminous minerals. It is
claimed that aluminium fluoride of the greatest purity can be
thus manufactured at a less cost than pure alumina can be
made.
More recently the method of production has been varied as
follows:! To produce aluminium fluoride free from silicon and
iron, calcined clay or kaolin is stirred in excess into dilute hy-
drofluoric acid, a 12 per cent, solution of which is recommended.
The violent reaction ensuing is moderated by cooling, so that
the temperature does not exceed 95°. After a few minutes the
* Bull, de la Soc. Chimique [2], xxi, 241.
t German Patent No. 69,791, August 20, 1892.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 73
liquor is neutralized, as may be tested by a drop giving a pure
yellow with tropaolin. This neutrality is essential to ensure
the solution being free from silica. Further, this neutrality
cannot be obtained using uncalcined clay, nor with clay which
has been too highly heated. The clay must be calcined at a
certain determined temperature, which can only be learned by
experience. The hot, neutral solution is cooled to a moderate
temperature and filtered quickly, washing the residue with hot
water. On an average the equivalent of 95 per cent, of the hy-
drofluoric? acid used can be obtained in the form of dissolved
aluminium fluoride. The solution will be free from dissolved
silica, but may contain iron, lead, arsenic or other accidental
impurities. In order to separate out pure aluminium fluoride
from this solution, Grabau has patented the following method of
procedure :* The solution is first treated with sulphuretted hy-
drogen gas, which precipitates any lead, copper, arsenic, etc.,
which may be present, and reduces any ferric salt present to the
ferrous state. Any other reducing agent could also be used to
effect this. The solution is filtered and slightly acidified, so
that a test drop turns red with tropaolin. A neutral solution
holding hydrogen sulphide would in the subsequent cooHng de-
posit traces of iron sulphide. The acidified solution is then
str-ongly cooled in a receptacle, which may be of sheet alumin-
ium. There at once separates out crystalline, hydrated alu-
minium fluoride, AIF3.9H2O. It is best to start the crystalliza-
tion by dropping in a trace of the crystallized salt. As soon as
the crystallization commences the temperature rises ; when it
again sinks to 0° by continuing the cooling, the crystallization
is ended. The thick crystal liquor is separated on filters or in
a centrifugal machine, into mother liquor and crystals; the
latter are washed with ice-cold water. These crystals are free
from iron, but if the solution had not been previously reduced,
noticeable quantities of ferric fluoride would have been in them.
These crystals are easily dried and the water driven off by
gentle heating.
♦German Patent No. 70,155, August 20, 1892.
1 7 i ALUMINIUM.
IV.
The Preparation of Aluminium Sulphide.
Until the researches of M. Fremy, no other method of pro-
ducing aluminium sulphide was known save by acting on the
metal with sulphur at a very high heat. Fremy was the first
to open up a diflferent method, and it may be that his discov-
eries will yet be the basis of successful industrial processes. In
order to understand just how much he discovered, w? here give
all that his original paper contains concerning this sulphide.*
"We know that sulphur has no action on silica or boric ox-
ide, magnesia, or alumina. I thought that it might be possible
to replace the oxygen by sulphur if I introduced or intervened
a second affinity, as that of carbon for oxygen. These decom-
positions produced by two affinities are very frequent in chem-
istry ; it is thus that carbon and chlorine, by acting simultane-
ously on silica or alumina, produce silicon or aluminium
chloride, while either alone could not decompose it ; a similar
case is the decomposition of chromic oxide by carbon bisul-
phide, producing chromium sesquisulphide. Reflecting on
these relations, I thought that carbon bisulphide ought to act
at a high heat on silica, magnesia, and alumina, producing
easily their sulphides. Experiment has confirmed this view.
I have been able to obtain in this way almost all the sulphides
which until then had been produced only by the action of sul-
phur on the metals.
" To facilitate the reaction and to protect the sulphide from
the decomposing action of the alkalies contained in the por-
celain tube which was used, I found it sometimes useful to mix
the oxides with carbon and to form the mixture into bullets
resembling those employed in the preparation of aluminium
chloride. I ordinarily placed the bullets in little carbon boats,
and heated the tube to whiteness in the current of vaporized
* Ann. de Chim. et de Phys. [3], 38, p. 312.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 75
carbon bisulphide. The presence of divided carbon does not
appear useful in the preparation of this sulphide.
" The aluminium sulphide formed is not volatile ; it remains
in the carbon boats and presents the appearance of a melted
vitreous mass. On contact with water it is immediately de-
composed :
A1,S, + 3H,0 = Al,03 + 3H,S.
" The alumina is precipitated, no part of it going into solu-
tion. This precipitated alumina is immediately soluble in weak
acids. The clear solution, evaporated to dryness, gives no
trace of alumina. It is on this phenomenon that I base the
method of analysis.
" Aluminium sulphide being non-volatile, it is always mixed
with some undecomposed alumina. It is, in fact, impossible to
entirely transform all the alumina into sulphide. I have heated
less than a gramme of alumina to redness five or six hours in
carbon bisulphide vapor, and the product was always a mixture
of alumina and aluminium sulphide. The reason is that the
sulphide, being non-volatile and fusible, coats over the alumina
and prevents its further decomposition. The alumina thus
mixed with the sulphide, and which has been exposed to a red
heat for a long time, is very hard, scratches glass, and is in
grains which are entirely insoluble in acids. By reason of this
property I have been able to analyze the product exactly, for
on treating the product with water and determining on the one
hand the sulphuretted hydrogen evolved, and on the other the
quantity of soluble alumina resulting, I have determined the
two elements of the compound. One gramme of my product
contained 0.365 grm. of aluminium sulphide, or 36.5 per cent.,
the remainder being undecomposed alumina."
The composition of this sulphide was—
Aluminium °-i37 g™- = 37-5 pef cent.
Sulphur 0.228 "=62.5
0.365 " lOO.O "
1/6 ALUMINIUM.
The formula AI2S3 requires —
Aluminium 36.3 per cent.
Sulphur 63.7 "
The above is the substance of Fremy's investigations and
results. Reichel* next published an account of further experi-
ments in this line. He found that by melting alumina and sul-
phur together no reaction ensued. In the case of magnesia, the
sulphide was formed if carbon was mixed with the magnesia
and sulphur, but this change did not alter the alumina. Hydro-
gen gas passed over a mixture of alumina and sulphur likewise
gave negative results. Sulphuretted hydrogen passed over ig-
nited alumina did not succeed. By filling a tube with pure alu-
mina, passing in hydrogen gas and the vapor of carbon bisul-
phide, the heating being continued until carbon bisulphide
condensed in the outlet tube, and then hydrogen being passed
through until the tube was cold, a product was obtained con-
taining aluminium sulphide and undecomposed alumina.
In 1886, the writer made a series of experiments on the pro-
duction and reduction of aluminium sulphide. Alumina, either
alone or mixed with carbon or with carbon and sulphur, was
put in porcelain or carbon boats into a hard glass or porcelain
tube. This was then heated and vapor of carbon bisulphide
passed through it. The product was analyzed according to
Fremy's directions. The proportion of aluminium sulphide
obtained in the product varied from 13 to 40 per cent. The
best result was obtained at the highest heat — almost whiteness.
The presence of sulphur or carbon, or both together, mixed
with the alumina, did not promote to any degree the formation
of a richer product. The conditions for obtaining the best re-
sults seem to be high heat and fine division of the alumina to
facilitate its contact with the carbon bisulphide vapor. The
product was light-yellow when not mixed with carbon, easily
pulverized, and evolved sulphuretted hydrogen gas energetically
* Jahresb. der Chemie, 1867, p. 155.
PREPARATION OF ALUMINIUM COMPOUNDS. 1 77
when dropped into water. Since carbon bisulphide can now be
manfactured at a very low price, say 2 to 3 cents per lb., it is
not impossible that it may be found profitable to produce
aluminium from its sulphide. In such a case, large retorts
would be used, a stirring apparatus would facilitate the forma-
tion of a richer product, and the unused carbon bisulphide
could be condensed and saved.
M. Comenge,* of Paris, proposed to prepare aluminium sul-
phide by using a clay retort similar to those used in gas-works,
filling it one- half its length with charcoal or coke and the other
half with alumina. The retort being heated to rednesss, sul-
phur is introduced at the coke end, when in contact with the
carbon it forms carbon bisulphide, which acts upon the alumina
at the other end, producing the sulphide.
Messrs. Reillon, Montague, and Bourgerel f obtained a pat-
ent in England for producing aluminium, in which aluminium
sulphide is obtained by mixing powdered alumina with 40
per cent, of its weight of charcoal or lampblack and formed
into a paste with a sufficient quantity of oil and tar. This is
then calcined in a closed vessel and an aluminous coke ob-
tained. This is broken into pieces, put into a retort, and
treated with carbon bisulphide vapor. The inventors state
that the reaction takes place according to the formula
2 A1,0, + 3C + 3CS, = 4A1,S, -^ 6C0.
PetitjeanI states that if alumina is mixed with tar or turpentine
and ignited in a carbon-lined crucible, and the coke obtained
mixed intimately with sulphur and carbonate of soda and ig-
nited a long time at bright redness, there results a double sul-
phide of aluminium and sodium, from which aluminium can be
easily extracted.
It has been stated § that if aluminium fluoride is heated with
* English Patent, 1858, No. 461.
t English Patent, No. 4,756, March 28, 1887.
JPolytechnisches Central. Blatt., 1858, p. 888.
§ Chemical News, i860.
12
178 ALUMINIUM.
calcium sulphide, aluminium sulphide results. F. Lauterborn*
also makes the same claim in a patent twenty years later, but
the possibility of this reaction taking place is not yet beyond
question.
* German Patent (D. R. P.), No. 14,495 (1880).
CHAPTER VII.
THE MANUFACTURE OF SODIUM.
Some years ago, in order to treat fully of the metallurgy of
aluminium it would have been as necessary to accompany it
with all the details of the manufacture of sodium as to give the
details of the reduction of the aluminium, because the manu-
facture of the, former was carried on solely in connection with
that of the latter. But now sodium has come out of the list of
chemical curiosities, and has become an article of commerce,
used for many other purposes than the reduction of aluminium.
In fact, the last four years has seen the almost total extinction
of the sodium processes of producing aluminium. If it be asked
why such a chapter as this is still retained in a treatise on alu-
minium, the answer is that for thirty years aluminium was
made solely by its use; sodium is bound up with the history of
aluminium ; and it is not impossible, though perhaps improba-
ble, that some improved form of sodium process, in which me-
tallic sodium is produced and at once utilized in the one ope-
ration, may yet find a footing in the aluminium industry. For
these and other reasons which might be advanced, the methods
of producing sodium are yet of considerable interest to the
worker in aluminium, and are therefore retained, with the addi-
tion of a few recent processes.
Davy to Deville (1808-1855).
Sodium was first isolated by Davy by the use of electricity in
the year 1808.* Later, Gay Lussac and Thenard made it by
decomposing at a very high temperature a mixture of sodium
carbonate and iron filings, f In 1808, also, Curaudau an-
* Phil. Trans., :8o8.
fRecherches Physico-chimiques, 1810.
(179)
i8o
ALUMINIUM.
nounced that he had succeeded in producing potassium or
sodium without using iron, simply by decomposing their car-
bonates by means of animal charcoal. Briinner, continuing
this investigation, used instead of animal charcoal the so-called
black flux, the product obtained by calcining crude tartar from
wine barrels. He was the first to use the wrought-iron mer-
cury bottles. The mixture was heated white hot in a furnace,
the sodium volatilized, and was condensed in an iron tube
screwed into the top of the flask, which projected from the fur-
nace and was cooled with water. In Brunner's experiments he
only obtained three per cent, of the weight of the mixture as
metallic sodium, the rest of the metal being lost as vapor.
Donny and Mareska gave the condenser the form which with
a few modifications it retains to-day.
It was of iron, 4 millimetres thick, and
was made in the shape of a book,
having a length of about 100 centi-
metres, breadth 50, and depth 6 (see
Fig. 9). This form is now so well
known that a further description is
unnecessary. With this condenser the
greatest difficulty of the process was
removed, and the operation could be
carried on in safety. This apparatus
was devised and used by Donny and Mareska in 1854, with the
supervision of Deville.
FlQ. 9.
Deville' s Improvements at Javel (1855).
The following is Deville's own description of the attempts
which he made to reduce the cost of producing sodium. As
far as we can learn these experiments were commenced in 1854,
but the processes about to be given are those which were car-
ried out at Javel, March to June, 1855. As the description
contains so many allusions to the difficulties met not only in pro-
ducing but also in handling and preserving sodium, its perusal
is yet of value to all concerned in this subject, although the
THE MANUFACTURE OF SODIUM. l8l
actual methods here described have been superseded by much
more economical ones.
Properties of sodium. — "The small equivalent of sodium and
the low price of sodium carbonate should long since have
caused it to be preferred to potassium in chemical operations,
but a false idea prevailed for a long time concerning the diffi-
culties accompanying the reduction. When I commenced
these researches the cost of sodium was at least double that of
potassium. In this connection I can quote from my memoir
published in the Ann. de Chim. et de Phys., Jan., i, 1855 : "I
have studied with care the preparation of sodium and its prop-
erties with respect to oxygen and the air, in order to solve the
difficulties which accompany its reduction and the dangers of
handling it. In this later respect, sodium is not to be com-
pared to potassium. As an example of how dangerous the
latter is, I will relate that being used to handle sodium and
wishing once to replace it with potassium, the simple rubbing
of the metal between two sheets of paper sufficed to ignite it
with an explosion. Sodium may be beaten out between two
sheets of paper, cut and handled in the air, without accident if
the fingers and tools used are not wet. It may be heated with
impunity in the air, even to its fusing point, without taking fire,
and when melted, oxidation takes place slowly, and only at the
expense of the moisture of the air. I have even concluded
that the vapor alone of sodium is inflammable, but the vivid
combustion of the metal can yet take place at a temperature
which is far below its boiling point, but at which the tension of
the metallic vapors has become sensible." I will add to these
remarks that sodium possesses two considerable advantages :
it is obtained pure at the first operation, and, thanks to a
knack which I was a long time in finding out, the globules of
the metal may be reunited and treated as an ordinary metal
when melting and casting in the air. I have thus been able to
dispense with the distillation of the raw products in the manu-
facture— an operation which had come to be behaved neces-
sary, and which occasioned a loss of 50 per cent, or so on the
1 82 ALUMINIUM.
return, without appreciable advantage to the purity of the
metal. The manufacture of sodium is in no manner encum-
bered by the carburetted products, or perhaps nitrides, which
are very explosive, and render the preparation of potassium so
dangerous. I ought to say, however, that by making potas-
sium on a large scale by the processes I am about to describe
for sodium, Rousseau Bros, have diminished the dangers of its
preparation very much, and practice the process daily in their
chemical works.
Method employed. The method of manufacture is founded
on the reaction of carbon on alkaline carbonate. This method
has been very rarely applied to sodium, but is used every day
for producing potassium. Brunner's process is, in fact, very
difficult to apply, great trouble being met, especially in the
shape of condenser used. It is Donny and Mareska who have
mastered the principles which should guide in constructing
these condensers.
Composition of mixtures used. The mixture which has given
me excellent results in the laboratory is :
Sodium carbonate 717 parts.
Wood charcoal 1 75 "
Chalk 108 "
1000
Dry carbonate of soda is used, the carbon and chalk pulver-
ized, the whole made into a paste with oil and calcined in a
crucible. The end of a mercury bottle, cut off, serves very
well, and can be conveniently closed. Oil may be used alto-
gether in place of charcoal, in which case the following pro-
portions are used :
Sodium carbonate 625 parts.
Oil 280 "
Chalk 95 "
That a mixture be considered good, it should not melt at the
temperature at which sodium is evolved, becoming liquid at
THE MANUFACTURE OF SODIUM. 1 83
this point and so obstructing the disengagement of the gas.*
But it should become pasty, so as to mold itself evenly against
the lower side of the iron vessel in which it is heated. The
considerable latent heat required by carbonic oxide and sodium
in assuming the gaseous state, is one cause of cooling which re-
tards the combustion of the iron. When soda salt is intro-
duced in place of dried soda crystals, the mixture, whatever its
composition, always melts, the gases making a sort of ebulli-
tion, the workmen saying that the apparatus " sputters." This
behavior characterizes a bad mixture. It has been demon-
strated to me that the economy made at the expense of a
material such as carbonate of soda, the price of which varies
with its strength in degrees, and which forms relatively a small
portion of the cost of sodium, is annulled by a decrease of 20 to
25 per cent, in the return of sodium. The oil used ought to be
dry and of long flame. It acts as a reducing agent, and also
furnishes during the whole operation hydrogenous gases, and
even, towards the close, pure hydrogen, which help to carry
the sodium vapor rapidly away into the condenser, and to
protect the condensed metal from the destructive action of the
carbonic oxide. Oil renders a similar service in the manu-
facture of zinc. The role of the chalk is easy to understand.
By its infusibility it decreases the liability of the mixture to
melt. Further it gives off carbonic acid, immediately reduced
by the carbon present to carbonic oxide. Now, the sodium
ought to be carried rapidly away out of the apparatus, because
it has the property of decomposing carbonic oxide, which is
simultaneously formed, within certain limits of temperature,
especially if the sodium is disseminated in little globules and
so presents a large surface to the destructive action of the gas.
It is necessary, then, that the metallic vapors should be rapidly
conducted into the condenser and brought into the liquid state
* It seems plain, however, granting that vapors would be evolved most freely from
2. perfectly infusible charge, that a pasty condition, such as is recommended in the
next sentence, would be the worst possible state of the charge for evolving gas, being
manifestly inferior to a completely fluid bath.— J. W. R.
1 84 ALUMINIUM.
— not into that state comparable to "flowers of sulphur," in
which the metal is very oxidizable because of its fine division.
A rapid current of gas, even of carbonic oxide, actively carries
the vapors into the condenser, which they keep warm and so
facilitate the reunion of the globules of sodium. At La
Glaciere and Nanterre a mixture was used in which the, pro-
portion of chalk, far from being diminished, was, on the con-
trary, increased. The proportions used were —
Sodium carbonate 40 kilos = 597 parts.
Oil 18 " =269 "
Chalk 9 " =134 "
67 1000
This quantity of mixture ought to give 9.4 kilos of sodium,
melted and cast into ingots, without counting the metal divided
and mixed with foreign materials, of which a good deal is
formed. This return would be one-seventh of the weight of
the mixture, or one-quarter of the sodium carbonate used.
Use of these mixtures. The carbonate of soda, charcoal, and
chalk ought to be pulverized and sieved, well mixed and again
sieved, in order to make a very intimate mixture ; the mixture
ought to be used as soon as possible after preparing, that it
may not take up moisture. The mixture may be put just as it
is into the apparatus where it should furnish sodium, but it may
very advantageously be previously calcined so as to reduce its
volume considerably, and so permit a greater weight being put
into the same vessel. I believe that whenever this calcination
may be made with economy, as with the waste heat of a fur-
nace, a gain is made by doing so, but the procedure is not in-
dispensable. However, the utility of it may be judged when
it is stated that a mercury bottle held two kilos of non-calcined
mixture, but 3.6 kilos were put into one when previously cal-
cined. These two bottles heated in the same fire for the same
time gave quantities of sodium very nearly proportional to the
weight of soda in them. In working under the direction of a
good workman, who made the bottles serve for almost four
THE MANUFACTURE OF SODIUM. 1 85
operations, I have been able to obtain very fine sodium at as
low a price as 9.25 francs per kilo. ($0.84 per pound). In the
manufacture of sodium by the continuous process, where the
materials may be introduced red hot into the apparatus, this
preliminary calcination is a very economical operation.
Apparatus for reducing, condensing, and heating. — M. Briin-
ner had the happy idea of employing mercury bottles in manu-
facturing potassium ; thus the apparatus for reduction was in the
hands of any chemist, and at such a low price that any one has
been able to make potassium without much trouble. These
bottles are equally suitable for preparing sodium, and the
quantity which may be obtained from such apparatus and the
ease with which they are heated, are such that they might have
been used a long time for the industrial manufacture, except
for two reasons which tend to increase the price of these bottles
continually. For some time a large number of bottles have
been sent to the gold workers of Australia and California, also
large quantities have been used in late years in preparing the
alkaline metals ; these two facts have diminished the number to
such a point that from 0.5 or i franc the price has been raised
to 2.5 or 3 francs. It has thus become necessary to replace
them, which has been done by substituting large wrought-iron
tubes which have the added advantage of being able to be
worked continuously. I will first describe the manufacture in
mercury bottles, which may still be very advantageously used
in the laboratory, and afterwards the continuous production in
large iron cylinders as now worked industrially.
Manufacture in mercury bottles. — The apparatus needed is
composed of a furnace, a mercury bottle, and a condenser.
The form of furnace most suitable is a square shaft, C (Fig.
10), the sides of which are refractory brick, while the grate G
ought to have movable grate bars, the furnace being connected
above with a chimney furnishing good draft. The flue F, con-
necting with the chimney, should have a damper, R, closing
tightly, and should lead exactly from, the centre of, the top of
the shaft, thus dividing the draft equally all over the grate.
1 86
ALUMINIUM.
Coke is charged through lateral openings at 0. A small open-
ing closed by a brick should be left a short distance above the
grate bars, in order to poke down the coke around the bottle
should it not fall freely. The space between the grate and
bottle should always be full of fuel in order to keep the iron of
the bottle from being burnt. In front of. the furnace is a square
opening, P, closed with an iron plate, which has a hole in it by
which the tube T issues from the furnace.
The mercury bottle is supported on two refractory bricks,
KK, cut on their top side to the curve of the bottle. These
Fig. 10.
should be at least 20 centimetres high to maintain between the
grate and the bottle a convenient distance. The illustration
gives the vertical dimensions correctly, but the horizontal
dimensions are somewhat shortened. There should be at least
12 centimetres between the bottle and sides of the furnace.
However, all these dimensions should vary with the strength of
the chimney draft and the kind of fuel used ; the furnace
should be narrower if the draft is very strong and the coke
dense. The iron tube T, which may conveniently be made of
a gun barrel, is either screwed into the bottle or it may be
simply fitted and forced into place, provided it hold tightly
THE MANUFACTURE OF SODIUM. 1 87
enough. It should be about 5 to 6 centimetres long, and
should project scarcely i centimetre from the furnace. The
end projecting should be tapered off in order to fit closely into
the neck of the condenser.
The condenser is constructed with very little deviation from
that given by Donny and Mareska (see Fig. 9, p. 180). I
have tried my best to make this apparatus as perfect as
possible, but have always reverted to the form described by
those authors ; yet even the very small differences I have made
are indispensable and must be rigidly adhered to if it is wished
to get the best results obtainable. Two plates of sheet iron, 2
to 3 millimetres thick, are taken and cut into the shape indi-
cated by Fig. II. One plate. A, remains flat except at the
point C, where it is drawn by hammering into a semi-
cylindrical neck of about 25 millimetres inside diameter. This
Fig. II.
iiiiii 111!
■corresponds with a similar neck in the other plate, so that on
joining the two there is a short cylinder formed. The edges of
the plate A are raised all around the sides about 5 to 6 milli-
metres, so that when the two plates are put together the longi-
tudinal section from £> to Cis as in Fig. 12. As to the end,
in one form the edge was not turned up, leaving the end open
as in Fig. 13. Another form, which I use when wishing to let
the sodium accumulate in the condenser till it is quite full, is
made by turning up the edge at the end all but a small space
left free, thus giving the end the appearance of Fig. 14, this
-device also being shown in Fig. 11. The gas evolved during
1 88 ALUMINIUM.
the reaction then escapes at the hole 0. The most rational
arrangement of the apparatus is that shown in Fig. 15. In this
condenser the lower part, instead of being horizontal, is in-
clined, and the end having two openings, O and 0' , the sodium
trickles out at the lower one as it condenses, while the gas es-
capes by the slightly larger upper opening. In placing the
plates together, the raised edges are washed with hme so as to
form a good joint with the flat plate, and the plates are kept
together by strong pressure grips.
To conduct the operation, the bottles are filled entirely with
mixture, the tube T adjusted, and then placed on the two sup-
ports, there being already a good bed of fire on the grate. The
front is put up, the shaft filled with coke, and the damper
opened. The gases disengaged from the bottle are abundant,
of a yellow color ; at the end of half an hour white fumes of
carbonate of soda appear. The condenser should not yet be
attached, but it should be noted if any sodium condenses on a
cold iron rod pushed into the tube, which would be indicated
by its fuming in the air. As soon as this test shows that sodium
is being produced, the condenser is attached and the fire kept
quite hot. The condenser soon becomes warm from the gases
passing through it, while the sodium condenses and flows out
at the end D (Fig. 15). It is received in a cast-iron basin L,
in which some non-volatile petroleum is put. When at the end
of a certain time the condenser becomes choked, it is replaced
by another which has been previously warmed up to 200° or
300° by placing it on top of the furnace. If the closed con-
denser is used, care must be taken to watch when it becomes
full, on the point of running from the upper opening, and the
condenser then replaced and plunged into a cast-iron pot full
of petroleum at a temperature of 150°. The sodium here
melts at the bottom of this pot and is ladled out at the end of
the day. The oil is generally kept up to 150° by the hot con-
densers being plunged in constantly. The pot ought to have
a close cover, to close it in case the oil takes fire ; the extinc-
tion of the fire can thus be assured and no danger results. If
THE MANUFACTURE OF SODIUM. 1 89
the oil fires just as a condenser is being introduced, the sodium
is run out in the air without igniting, the only drawback being
that the condenser must be cleaned before using again. This
method occasions a large loss of oil, however, and has been
completely abandoned for the other form of condensers. When
the operation proceeds well only pure sodium is obtained, the
carbonized products which accompany in so provoking a man-
ner the preparation of potassium not occurring in quantity
sufficient to cause any trouble. Before using a condenser a
second time it is put on a grating over a basin of petroleum
and rubbed with a chisel-pointed tool in order to remove any
such carbonized products. From time to time this material is
■collected, put into a mercury bottle, and heated gently. The
oil first distils, and is condensed in another cold bottle. The
fire is then urged, a condenser attached, and the operation pro-
ceeds as with a fresh charge, much sodium being thus recov-
ered.
The raw sodium is obtained from the bottles in quantities
of over half a kilo ; it is perfectly pure, dissolving in absolute
alcohol without residue. It is melted and moulded into ingots
just as lead or zinc. The operation I have described is exe-
cuted daily, and only once has the sodium ignited. To prevent
such accidents it is simply necessary to keep water away from
the apparatus. The reduction of carbonate of soda and the
production of sodium are such easy operations that when tried
by those conversant with the manufacture of potassium or who
have read about the difficulties of the production of sodium,
success is only gained after several attempts — the failure being
due solely to excess of precautions. The reduction should be
carried on rapidly, so that a bottle charged with two kilos of
rriixture may be heated and emptied in, at most, two hours. It
is unnecessary to prolong the operation after the yellow flame
stops issuing from the condenser, for no more sodium is ob-
tained and the bottle may frequently be destroyed. The
temperature necessary for the reduction is not so high as it has
teen so far iiriagined. M. Rivot, who has assisted in these ex-
I go ALUMINIUM.
periments, thinks that the bottles are not heated higher than
the retorts in the middle of the zinc furnaces at Vielle Mon-
tagne. I have been even induced to try cast-iron bottles, but
they did not resist the first heating, without doubt because they
were not protected from the fire by any luting or covering. But
I was immediately successful in using cast-iron bottles decar-
burized by the process used for making malleable castings.
The mercury bottles heated without an envelope ought to serve
three or four operations when entrusted to a careful workman.
Besides all these precautions, success in this work depends
particularly on the ability and experience of the workman, who
can at any time double the cost of the sodium by carelessness
in managing the fire. _
Continuous manufacture in cylinders. It might be thought
that by increasing proportionately in all their parts the dimen-
sions of the apparatus just described, it would be easy to pro-
duce much larger quantities of sodium. This idea, which
naturally presented itself to me at once, has been the cause of
many unfruitful attempts, into the details of which I will not
enter. I must, however, explain some details which may ap-
pear insignificant at first sight, but which were necessitated
during the development of the process. For instance, it will
perhaps look irrational for me to keep the same sized outlet
tubes and condensers that were used with the mercury bottles,
for tubes five times as large ; but I was forced to adopt this
arrangement after trying the use of tubes and condensers of all
sizes ; indeed, it is fortunate for the success of the operation
that this was so, for it became very injurious to the workmen
to handle the large and weighty apparatus in the face of a large
sodium flame.
The mixture of sodium carbonate and carbon is made in the
manner already described. I would say again that a previous
strong calcination of the materials presents a great advantage^
not only because it permits putting a much larger weight into
the retorts at once, but also that, being more compact, the mix-
ture will not rise as powder and be violently thrown out of the
THE MANUFACTURE OF SODIUM.
191
Strongly-heated retorts. The mixture should also be calcined
as needed, and used to fill the tubes while still red hot. When
cold, uncalcined mixture is used, it is put into large cartridges
of thick paper or canvas, 8 centimetres diameter and 35 cen-
timetres long.
The furnace and tubes are shown in section in Fig. 16. The
tubes T are 120 centimetres long, 14 centimetres inside
diameter, and 10 to 12 millimetres in thickness. They are
formed from one piece of boiler iron, bent and welded along
Fig. 16.
one side. The iron plate P which closes one end is about 2
centimetres thick, and pierced on one of its edges quite close
to the side of the cylinder by a hole in which is screwed or
fitted an iron tube, Z, 5 to 6 centimetres long and 15 to 20
millimetres inside diameter, and tapering off at the end to fit
into the condenser neck. The other end of the tube is closed
by an iron plug, 0, terminated by a knob. The welded side of
the tube is kept uppermost. These iron tubes should not, like
the mercury bottles, be heated in the bare fire ; it is necessary
to coat them with a resistant luting which is itself enveloped by
a refractory jacket i centimetre thick, 22 centimetres interior
192 ALUMINIUM.
diameter, and the same length as the retorts. This protection
is commenced by plastering the retorts over with a mixture of
equal parts of raw clay and stove ashes, which have been made
into a paste with water and as much sand worked into the mix-
ture as it will take without losing its plasticity, also adding
some horse manure. This luting should be dried slowly, and
the tube thus prepared is introduced into the refractory jacket,
the open space between the two being filled with powdered
refractory brick. Finally, luting is put on the iron plate P, so
that no part of it is exposed to the flame.
The furnace I have used is a reverberatory, but I do not re-
commend its use without important modifications, because it
does not realize all the conditions of easy and economic heat-
ing. The grate is divided into two parts by a little wall of re-
fractory brick, on which the middle of the reduction cylinders
rests. The tubes are thus seen to be immediately over the bed
of fuel. The top of the bridge is a little higher than the upper
edge of the cylinders, this and the very low arch making the
flame circulate better all around the tubes. A third cylinder
might easily be placed above these two, and be heated satis-
factorily, without any more fuel being burnt. This reverbera-
tory receives on its bed the mixtures to be calcined, placed in
cast-iron or earthen pots according to their composition.
When the furnace is kept going night and day producing
sodium, the temperature rises on the bed to clear cherry-red,
and experience has shown that other reducing cylinders might
be placed there, under such conditions, and be heated suf-
ficiently for the reduction.
All that I have said of the manufacture of sodium in mercury
bottles applies equally to its manufacture in cylinders. The
only difference consists in the charging and discharging, and I
have only to add several precautions to be taken. On intro-
ducing the cartridges containing uncalcined mixture, only 8 to
9 kilos can be heated at once ; double as much can be used of
previously-calcined mixture. The plug 0 is put in place, not
so tightly that it cannot easily be taken out again ; a little
THE MANUFACTURE OF SODIUM. 1 93
luting stops all leakages which show themselves. The reduc-
tion lasts about four hours. When it is finished, a little water is
thrown on the plug 0, and it is easily loosened and removed.
On looking into the cylinder, the cartridges are seen to have
kept their shape, but have shrunken so much that their diameter
is only about 2 to 3 centimetres ; they are very spongy. This
shows that the mixture has not melted ; the remainder is prin-
cipally lime and carbon, and free from sodium carbonate.
While opening the cylinder, a bright-red-hot iron is thrust into
the outlet tube L, to keep dirt from getting into it, and it is
kept in until the charging is finished. The cartridges are put
in by means of semi-cylindrical shovels. The sudden heating
of the mixture disengages soda dust from uncalcined mixtures,
which is very disagreeable to the workmen. The cylinders are
closed, and when the sodium flame appears at the outlet tube
the condenser is attached, and the operation proceeds as
already described.
The envelopes of the cylinders are thick enough to prevent
the distillation of the sodium being in any way affected by the
accidental causes of cooling the fire. So when fresh fuel is
charged or the door of the reverberatory is opened, causing the
draft to cease almost entirely in the fire-place, the operation
should not suffer by these intermittences, provided.that they are
not too long prolonged. In short, when operating in cylinders,
the production of sodium is easier, less injurious to the work-
men, and less costly in regard to labor and fuel than when
working with mercury bottles. At times, after working a fort-
night with many interruptions dangerous for the apparatus, my
experiment has been suddenly ended. The furnace was intact ;
the envelopes of the tubes were split open, and the luting on
the tubes found to be compact and coherent, but without traces
of fusion, showing perfect resistance. The iron tubes mean-
while had not suffered inside or out, and seemed as though
they would last indefinitely. I attribute this success to the par-
ticular care given to the composition of the jackets, and to the
perfection with which the tubes had been welded. Only on
13
194 ALUMINIUM.
one of the tubes was a very slight crack found, on a part not
the most highly heated, and not sufficient to cause the tube to
be discarded.
Tissier Bros.' method of procedure. (1856). As related in
the historical treatment of the subject (p. 13), Deville charged
the Tissier Bros, with appropriating from him the process for
the continuous production of sodium in cylinders, which, as
just given, was devised during the experiments at Javel. On
the other hand, the Tissier Bros, asserted their right to the
process, patenting it, and using it in the works started at Rouen
in the latter part of 1855. The following details are taken
from Tissier's " Recherche de 1' Aluminium," only such being
selected as supplement Deville's description, which has just
been given.
The sodium carbonate is first well dried at a high temper-
ature, then mixed with well-dried pulverized charcoal and chalk,
ground to the finest powder, the success of the operation de-
pending on the fineness of this mixture. The proportions of
these to use are various. One simple mixture is of
Sodium carbonate 566
Coal 244
Chalk 95
Coke 95
1000
Another contains —
Sodium carbonate 615
Coal 277
Chalk 108
1000
The addition of chalk has the object of making the mixture
less fusible and more porous, but has the disadvantage that the
residue remaining in the retort after the operation is very im-
pure, and it is impossible to add any of it to the succeeding
charge ; and also, some of it being reduced to caustic lime
forms caustic alkali with some sodium carbonate, which is then
THE MANUFACTURE OF SODIUM.
195
lost. WheD the mixture is well made it is subjected to a pre-
limiinary calcination. This is done in cast-iron cylinders, two
of which are placed side by side in a furnace and heated to
redness (see Fig. 17). This is continued till all the moisture,
carbonic acid, and any carburetted hydrogen from the coal,
cease coming off. The mass contracts, becomes white and
somewhat dense, so that a larger amount of the mixture can
now be treated in the retorts where the sodium is evolved. As
soon as the outcoming gases burn with a yellow flame, showing
Fig. 17.
sodium coming ofT, the calcination is stopped. The mixture is
then immediately drawn out on to the stone floor of the shop,
where it cools quickly and is then ready for the next operation.
This calcination yields a mixture which without any previous
reactions is just ready to evolve sodium when brought to the
necessary temperature. This material is made into a sort of
cylinder or cartridge and put into the decomposition retorts
(see Fig. 16). The charging should be done quickly. The
final retorts are of wrought-iron, since cast-iron would not
stand the heat. At each end this retort is closed with wrought-
iron stoppers and made tight with fire-clay. Through one
stopper leads the pipe to the condenser, the other stopper is
the one removed when the retort is to be recharged. These
retorts are placed horizontally in rows in a furnace. Usually
four are placed in a furnace, preferably heated by gas, such as
the Siemens regenerative furnace or Bicheroux, these being
196 ALUMINIUM.
much more economical. In spite of all these precautions the
retorts will be strongly attacked, and in order to protect them
from the destructive action of a white heat for seven or eight
hours they are coated with some kind of fire-proof material.
The best for this purpose is graphite, which is made into cylin-
ders enclosing the retorts, and which can remain in place till
the furnace is worn out. These graphite cylinders not only
protect the iron retorts, but prevent the diffusion of the gas-
eous products of the reaction into the hearth, and so support
the retorts that their removal from the furnace is easily accom-
plished. Instead of these graphite cylinders the retorts may
be painted with a mixture that melts at white heat and so en-
amels the outside. A mixture of alumina, sand, yellow earth,
borax, and water-glass will serve very well in many cases. We
would remark that the waste gases from this furnace can be
used for the calcining of the mixture, or even for the reduction
of the aluminium by sodium, where the manufacture of the
former is connected with the making of the sodium.
As for the reduction of the sodium, the retort is first heated
to redness, during which the stopper at the condenser end of
the retort is left off. The charge is then rapidly put in, and the
stopper at once put in place. The reaction begins almost at
once and the operation is soon under full headway, the gases
evolved burning from the upper slit of the condenser tube with
a flame a foot long. The gases increase in volume as the
operation continues, the flame becoming yellower from sodium
and so intensely bright as to be insupportable to look at. Now
has come the moment when the workman must quickly adapt
the condenser to the end of the tube projecting from the retort,
the joint being greased with tallow or parafHn. The sodium
collects in this in a melted state and trickles out. The length
of the operation varies, depending on the intensity of the heat
and the quantity of the mixture ; a charge may sometimes be
driven over in two hours, and sometimes it takes eight. We
can say, in general, that if the reaction goes on quickly a some-
what larger amount of sodium is obtained. The higher the
THE MANUFACTURE OF SODIUM. 1 97
heat used, however, the quicker the retorts are destroyed. The
operation requires continual attention. From time to time, a
workm-an with a prod opens up the neck of the condenser,
but if care is not taken the metal overflows ; if this happens,
the metal overflowing is thrown into some petroleum, while
another man replaces the condenser with an empty one. The
operation is ended when the evolution of gas ceases and the
flame becomes short and feeble, while the connecting tube be-
tween the retort and condenser keeps clean and does not stop
up. As soon as this occurs, the stopper at the charging end
is removed, the charge raked out into an iron car, and a new
charge being put in, the operation continues. After several
operations the retorts must be well cleaned and scraped out.
The sodium thus obtained is in melted bits or drops, mixed
with carbon and sodium carbonate. It must, therefore, be
cleaned, which is done by melting it in a wrought-iron kettle
under paraffin with a gentle heat, and then casting it into the
desired shapes. The sodium is kept under a layer of oil or
any hydrocarbon of high boiling point containing no oxygen.
Tissier gives the reaction as —
Na2C03+2C=3CO+2Na.
The sodium is condensed, while the carbonic oxide, carrying
over some sodium, burns at the end of the apparatus. This
would all be very simple if the reaction of carbonic oxide on
sodium near the condensing point did not complicate matters,
producing a black, infusible deposit of sodium monoxide
(Na^O) and carbon, which on being melted always give rise to
a loss of sodium.
Deville's Improvements at La Glacier e (1857).
At this works Deville tried the continuous process of manu-
facturing sodium in cylinders on a still larger scale, with the fol-
lowing results, as described by Deville himself: —
" We made no change in the composition of the mixtures used
198 ALUMINIUM.
from those already described, or in the form or size of the iron
tubes or the method of condensation ; but we worked with six
cylinders at a time in a furnace similar to the puddling furnaces
of M. Guadillot, the tubes being protected by refractory envel-
opes. The cylinders were so arranged on the hearth that the
flame bathed all parts of their surface. A low brick wall ex-
tends down the centre of the hearth, supporting the middle of the
cylinders, which extend across it. The hearth is well rammed
with refractory sand, and the space between it and the bottom
of the cylinder serves as a passage-way for most of the flame.
" Our six cylinders worked satisfactorily for five days. We
were able to observe that they were all heated with remarkable
uniformity, and that the heat was sufficient all round them. It
also appeared that the rear end of the cylinders required only
a hermetic seal. Indeed, as soon as the operation was well
under way and sodium distilling off, some of it condensed and
oxidized in the cool parts of the apparatus, forming a sort of
plug of carbonate and carbides of sodium, which the vapor and
gases could no longer penetrate. We were thus able for a
long time to distil sodium away from one of our tubes which
was entirely opened at the rear.
" This new furnace worked so well that we were hopeful of
complete success, when an accident happened which compelled
the stopping of the experiment. The iron tubes had been
ordered 1.20 metres long, the size of the hearth calculated ac-
cordingly, but they were delivered to us only 1.05 metres long.
We made use of these, with the result that the rear ends be-
came red-hot during the operation and allowed sodium vapors
to leak through. These leaked through the luting, and escap-
ing into the furnace, melted the envelopes very rapidly.
"In another attempt, in which this fault was avoided, we were
unsuccessful because the envelopes gave way at the first heat-
ing up, both they and the iron tubes being of inferior quality.
We were considerably inconvenienced by the failure of these
experiments, which caused considerable expense and gave no
very definite results. Just then a new sort of apparatus was
THE MANUFACTURE OF SODIUM. 1 99
devised, a description of which is given later on. It will be
seen that we were compelled to employ tubes of very small
value, so that their destruction in case of accident involved no
great loss, and to heat each one by an independent fire, so that
the stoppage or destruction of one cylinder would not necessitate
the stoppage or endanger the safety of the neighboring ones."
Cast-iron vessels. Deville tried at La Glaciere, as well as at
Javel, to utilize cast-iron vessels for producing sodium. Deville
states the difficulties which caused their use to be unsuccessful
to be as follows :
"The result was always unfavorable. Sodium is obtained, but
as soon as its production becomes rapid the vessel melts and
the operation is quickly ended. This follows because the tem-
perature necessary for the production of the metal is far from
being sufficient for producing it in large quantities at once ; and
we know that this is the one condition for condensing the so-
dium well and obtaining it economically. This observation led
me to think that by diminishing very much the temperature of
the furnace, large apparatus of cast-iron with large working
surface could be used, thus making at a time a large amount of
metallic vapor which could be condensed in recipients of ordi-
nary size. The whole large apparatus would thus have the out-
put of a smaller one worked at a higher temperature. My ex-
perience has shown me that in large-sized tubes heated to a
low temperature there is formed in a given time about as much
sodium as from a single mercury bottle at a much higher heat.
This is the reason why larger condensers are not necessary
with the larger tubes. Before knowing this fact, I tried a large
number of useless experiments to determine the size of con-
densers suitable for large apparatus. It is on this principle
that I have long been endeavoring to make sodium without
working at high temperatures, and using less costly and more
easily protected apparatus."
Improvements used at Nanterre (1859).
The method used here was exactly that already described,
200 ALUMINIUM.
the improvements being solely in details of the apparatus.
These are described by Deville as follows : —
" The experiments made at Javel and the continuous process
used at Glaciere have shown us in the clearest manner the ab-
solute necessity of efficient protection for the iron cylinders, for
without this protection the method cannot be practiced with
economy. Further, experiments in this direction are very
costly, for the failure of a tube stops the working of a large
number of cylinders, and often compromises the brick-work of
the furnace itself. We therefore came to the conclusion that
for making the small quantity of sodium we required, 300 to 500
kilos a month, it would be better to employ smaller apparatus,
independent of each other and easy to replace.
" The iron tubes are made of thinner iron and at very little ex-
pense, by taking a sheet of iron, curving it into a cylinder and
riveting the seam. This tube resembles very closely those
used at Javel, shown in Fig. 16, but of smaller dimensions. It
is closed at each end by cast-iron plugs, one of which has a
hole for the outlet tube. These cylinders are filled with sodium
mixture and placed in furnaces of the form of Fig. 10, except it
is necessary to have openings in the back and front of the fur-
nace so that the cast-iron plugs closing the cylinders may be
outside, to prevent their melting. We used coke at first for
fuel, fed around the cylinders, but M. Morin has since placed the
tubes out of direct contact with the fuel, uses soft coal, and heats
the tubes by contact with the flame and by radiation. In the
latest form used, two cylinders are placed in each furnace, and,
in general, they serve for two or three operations. All that has
been said in connection with the manufacture in mercury bot-
tles is immediately applicable to the manufacture in cylinders
of this kind, the capacity of which may vary from two to six or
eight litres, without any change in the manner of using them.
We have, however, adopted altogether condensers of cast-iron.
The neck is cylindrical and belongs only to one-half of the ap-
paratus, the neck end of the other plate being beveled and fit-
ting closely against a recess in the other plate."
THE MANUFACTURE OF SODIUM. 20I
The foregoing shows the sodium industry as it was perfected
by Deville, in 1859, and as it remained for twenty-five years
without sensible change. The cost of sodium by this process
is stated to have been, in 1872, as follows: —
Manufacture of one kilo of sodium.
Soda 9.35 kilos @ 32 fr. per 100 kilos = 3 fr. 9 cent.
Coal 74.32 " " 1.40" " " " = I " 4 "
Wages 3 " 73 "
Expenses 3 " 46 "
Total 1 1 fr. 32 cent.
which is equal to $1 per lb. The larger part of the expense
account is the cost of retorts or tubes in which the operation
takes place, and which are so quickly destroyed that the re-
placing of them forms nearly one-quarter of the cost of the
metal.
Minor Improvements (185 9- 1888).
An experiment made by Deville in 1864* is of considerable
interest in connection with some more recent processes. Guy
Lussac and Thenard having observed that caustic potash is re-
duced by iron, Deville took a mercury bottle with an aperture
above and one below, to which was fitted an iron tube and a
sodium condenser. Finely divided iron, reduced by hydrogen,
was put into the bottle, and when red hot, caustic soda was in-
troduced through the upper aperture. The iron was strongly
acted upon, and in less than 20 minutes Deville obtained y^ a
kilo of pure sodium. The reduction was stopped by a mixture
of soda and iron oxide filling up the lower opening. The ar-
rangement and reactions suggest strongly some later processes.
Why Deville did not continue on this line, I cannot say.
R. Wagnerf uses paraffin in preference to paraffin oil in
which to keep the sodium after making it. Only pure paraffin,
which has been melted a long time on a water-bath, and all its
water driven off, can be used. The sodium to be preserved is
* Lef ons de Chemie, 1864-5, P- 336- + Dingier, 1883, p. 252.
202 ALUMINIUM.
dipped in the paraffin melted on a water-bath, and kept at no
higher heat than 55° C, and the metal is thereby covered with a
thick coat of paraffin which protects it from oxidation, and may
then be put up in wooden or paper boxes. When the metal is
to be used, it is easily freed from paraffin by simply warming
it, since sodium melts at 95° to 96° C, and the paraffin at 50°
to 60°.
The reduction of potassium carbonate by carbon requires a
much less degree of heat than that of sodium carbonate, and
therefore many attempts have been made to reduce potassium
and sodium together, under circumstances where sodium alone
would not be reduced. Dumas* added some potassium car-
bonate to the regular sodium mixture; and separated the
sodium and potassium from each other by a slow, tedious oxi-
dation. R. Wagnerf made a similar attempt. He says that
not only does the reduction of both metals from a mixture of
their carbonates with carbon work easier than sodium carbonate
alone with carbon, but even caustic soda may be used with
potassium carbonate and carbon. Also, the melting point of
potassium and sodium alloyed is much lower than that of either
one alone, in consequence of which their boiling point and the
temperature required for reduction are lower.
J. B. Thompson and W. WhiteJ specify mixing dry sodium
carbonate with a liquid carbonaceous material, preferably tar,
driving off all volatile matter in iron pots at a low heat, and
then distilling in a tubular fire-clay retort connected with a
tightly-closed receiver containing a little paraffin oil to ensure a
non-oxiding atmosphere, and also provided with a small escape
pipe for carbonic oxide. This process gave great prospects of
success when tried in the laboratory, but on a manufacturing
scale it failed for the reason (assigned by Mr. Thompson) that
the sheet-iron tray, designed to keep the material from attack-
ing the retort, absorbed carbon at about 1000° C. and fused,
after which no sodium was produced, since the material took
* Handbuch der Angewandten Chemie, 1830, ii. 345.
t Dingier, 143, 343- J English Patent 8426, June 11, 1887.
THE MANUFACTURE OF SODIUM. 203
up silica from the retort, absorbing so much that the carbon no
longer decomposed it.
H. S. Blackmore,* of Mount Vernon, U. S. A., patents the
following process of obtaining sodium: —
Calcium hydrate 273^ parts.
B erric oxide 31 "
Dry sodium carbonate 31 "
Charcoal loj!^ "
are intimately mixed and subjected to a red heat for 20 min-
utes, afterwards to a white heat. Caustic soda is first produced,
the carbon reduces the ferric oxide, producing iron, which in
its turn reduces the caustic soda, and sodium vapors distil.
The residue consists of ferric oxide and lime, and is slaked and
used over.
O. M. Thowlessf of Newark, N. J., claims to place a retort in
a furnace, providing it on one side with an arm through which
carboniferous material can be supplied, on the other side with a
similar arm (surrounded by flues), into which caustic soda or
sodium carbonate is charged — a valve controlling their flow into
the retort. Outside the furnace and on top of it is a flat con-
denser into which the sodium vapor passes.
G. A. JarvisI patents the replacement of the iron tubes or
crucibles used in the manufacture of sodium, by fire-clay ap-
paratus lined with basic material, such as strongly burnt mag-
nesia with 10 per cent, of fluorspar.
Castner's Process (1886).
The first public announcement of this process was through
one of the New York daily journals,^ and as the tone of the
article is above that of the usual newspaper reports, and the
expectations contained in it were subsequently more than
realized, we cannot better introduce a description of this process
than by quoting the paragraph referred to : —
♦English Patent 15 156, Oct. 22, 1888. f English Patent 12486 (1887).
X English Patent 4842, March 31, 1888. § New York World, May 16, 1886.
204 ALUMINIUM.
"When sodium was reduced in cost to $1.50 per lb. it was
thought to have touched a bottom figure, and all hope of mak-
ing it any cheaper seemed fruitless. This cheapening was not
brought about by any improved or new process of reduction,
but was owing simply to the fact that the aluminium industry
required sodium, and by making it in large quantities its cost
does not exceed the above-mentioned price. The retail price
is now $4.00 per lb. The process now used was invented by
Briinner, in 1808, and up to the present time nothing new or
original has been patented except three or four modifications of
his process which have been adopted to meet the requirements
of using it on a large scale. Mr. H. Y. Castner, whose labora-
tory is at 218 West Twentieth Street, New York, has the first
patent ever granted on this subject in the United States, and
the only one taken out in the world since 1808. Owing to
negotiations being carried on, Mr. Castner having filed appli-
cations for patents in various foreign countries, but not having
the patents granted there yet, we are not at liberty to state his
process fully. The metal is reduced and distilled in large iron
crucibles, which are raised automatically through apertures in
the bottom of the furnace, where they remain until the reduc-
tion is completed and the sodium distilled. Then the crucible
is lowered, a new one containing a fresh charge is substituted
and raised into the furnace, while the one just used is cleaned
and made ready for use again. The temperature required is
very moderate, the sodium distillling as easy as zinc does when
being reduced. Whereas by previous processes only one-third
of the sodium in the charge is obtained, Mr. Castner gets
nearly all, for the pots are nearly entirely empty when with-
drawn from the furnace. Thus the great items of saving are
two or three times as much metal extracted from a given
amount of salt, and cheap cast iron crucibles used instead of
expensive wrought-iron retorts. Mr. Castner expects to pro-
duce sodium at 25 cents per lb., thus solving the problem of
cheap aluminium, and with it magnesium, silicon, and boron,
all of which depend on sodium for their manufacture. Thus
THE MANUFACTURE OF SODIUM. 205
the production of cheap sodium means much more than cheap
aluminium. Mr. Castner is well known in New York as a
chemist of good standing, and has associated with him Mr. J.
H. Booth and Mr. Henry Booth, both well known as gentlemen
of means and integrity."
The following are the claims which Mr. Castner makes in
his patent:*
1. In a process for manufacturing potassium or sodium, per-
forming the reduction by diffusing carbon in a body of alkali
in a state of fusion at moderate temperatures.
2. Performing the reduction by means of the carbide of. a
metal or its equivalent.
3. Mechanically combining a metal and carbon to increase
the weight of the reducing material, and then mixing this pro-
duct with the alkali and fusing the latter, whereby the reducing
material is held in suspension throughout the mass of fused
alkali.
4. Performing the deoxidation by the carbide of a metal or
its equivalent.
For an explanation of the principles made use of in the
above outlined process we will quote from a lecture delivered
by Mr. Castner at the Franklin Institute, Philadelphia, October
1 2th, 1886. That Institution has since bestowed on Mr. Cast-
ner one of its gold medals as a recognition of the benefit to
science accruing from his invention.
" In the ordinary sodium process, lime is added to the reduc-
ing mixture to make the mass refractory, otherwise the alkali
would fuse when the charge is highly heated, and separate from
the light, infusible carbon. The carbon must be in the propor-
tion to the sodium carbonate as four is to nine, as is found
needful in practice, so as to assure each particle of soda in the
refractory charge having an excess of carbon directly adjacent
or in actual contact. Notwithstanding the well-known fact that
sodium is reduced from its oxide at a degree of heat but slightly
exceeding the reducing point of zinc oxide, the heat necessary
* U. S. Pat. No. 342,897, June i, 1886. Hamilton Y. Castner, New York,
206 ALUMINIUM.
to accomplish reduction by this process and to obtain even
one-third of the metal in the chai-ge, closely approaches the
melting point of wrought-iron.
" In my process, the reducing substance, owing to its com-
position and gravity, remains below the surface of the molten
salt, and is, therefore, in direct contact with fused alkali.
The metallic coke of iron and carbon contains about 30 per
cent, carbon and 70 per cent, iron, equivalent to the formula
FeCj. I prefer to use caustic soda, on account of its fusibility,
and mix with it such quantity of so-called ' carbide ' that the
carbon contained in the mixture shall not be in excess of the
amount theoretically required by the following reaction: —
3NaOHf FeC,=--3Na4-Fe + CO f CO.+sH ;
or, to every 100 lbs. of pure caustic soda, 75 lbs. of 'carbide,'
containing about 22 lbs. of carbon.
" The necessary cover for the crucible is fixed stationary in
each chamber, and from this cover a tube projects into the con-
denser outside the furnace. The edges of the cover are convex,
those of the crucible concave, so that when the crucible is raised
into position and held there, the tight joint thus made prevents
all leaking of gas or vapor. Gas is used as fuel, and the re-
duction begins towards 1000° C. As the dharge is fused, the
alkali and reducing material are in direct contact, and this fact,
together with the aid rendered the carbon by the fine iron, in
withdrawing oxygen from the soda, explains why the reduction is
accomplished at a moderate temperature. Furthermore, by
reducing from a fused mass, in which the reducing agent re-
mains in suspension, the operation can be carried on in crucibles
of large diameter, the reduction taking place at the edges of the
mass, where the heat is greatest, the charge flowing thereto from
the centre to take the place of that reduced.
" I am enabled to obtain fully 90 per cent, of the metal in the
charge, instead of 30 per cent, as formerly. The crucibles,
after treatment, contain a little carbonate of soda, and all the
iron of the 'carbide' still in a fine state of division, together
THE MANUFACTURE OF SODIUM. 207
with a small percentage of carbon. These residues are treated
with warm water, the solution evaporated to recover the car-
bonate of soda, while the fine iron is dried, and used over again
for 'carbide.' "
Mr. Castner having demonstrated in his New York laboratory
the success of his process, went to England, and for several
months during the winter of 1886-7 was engaged in building
and working a large sodium furnace. This was successfully car-
ried out near London, the inventor being assisted by Mr. J.
MacTear, F. C. S., who, in March, 1887, read a description of
this furnace and the results obtained before the Society of
Chemical Industry. During the working of this furnace it was
inspected by many chemical and metallurgical authorities, who
were completely satisfied as to its success. As the furnace
then described differed in a few details from the one just re-
ferred to, it may be well to extract the essential particulars from
Mr. MacTear's paper — on the ground that the importance of
this invention justifies a complete discussion of its develop-
ment:—
" Since Mr. Castner's paper upon his process, which was
read before the Franklin Institute of Philadelphia, October 12,
1886, several slight changes in the mode of carrying on this
process have been made. These have been brought about by
the experience gained from the actual working of the process
upon a commercially large scale.
"The reactions by which the sodium is produced are some-
what difficult to describe, as they vary somewhat according to
the mixture of materials and temperature employed in the re-
duction. The mixture and temperature which it is now pre-
ferred to use is represented by the reaction : —
6NaH0 + FeC2= 2Na2CO, + 6H + Fe + zNa.
" In place of using an actual chemical compound of iron and
carbon, as expressed by the above reaction, a substitute or
equivalent is prepared as follows : To a given quantity of melted
pitch is added a definite proportion of iron in a fine state of
208 ALUMINIUM.
division. The mixture is cooled, broken up into lumps, and
cooked in large crucibles, giving a metallic coke consisting of
carbon and iron, the proportions of each depending upon the
relative quantities of pitch and iron used. This metallic coke,
after being finely ground, provides a substance having the iron
and carbon in a like proportion to an iron carbide, and from
which neither the iron nor carbon can be separated by mechan-
ical means. The fine iron is conveniently prepared by passing
carbonic oxide and hydrogen in a heated state, as obtained
from an ordinary gas producer, over a mass of oxide of iron
commercially known as 'purple ore,' heated to a temperature
of about 500° C.
" In producing sodium, caustic soda of the highest obtain-
able strength is used, and there is mixed with it a weighed
quantity of the so-called ' carbide,' sufficient to furnish the
proper amount of carbon to carry out the reaction indicated
above. The crucibles in which this mixture is treated are made
of cast-steel, and are capable of containing a charge of 15 lbs.
of caustic soda, together with the proper proportion of the
• carbide.'
"After charging a crucible with the above mixture, it is
placed in a small furnace where it is kept at a low heat for
about thirty minutes, during which time the mass fuses, boils
violently, and a large part of the hydrogen is expelled by the
combined action of the iron and carbon, the ' carbide,' owing
to its gravity, remaining in suspension throughout the fused
soda. At the end of the time stated, the contents of the cru-
cible have subsided to a quiet fusion. The crucible is then
lifted by a pair of tongs on wheels and placed upon the plat-
form of the elevating gear, as shown in the drawing, (Fig. 18)
and raised to its position in the heating chamber of the main dis-
tilling furnace. The cover which remains stationary in the fur-
nace has a convex edge, while the crucible has a groove round the
edge into which the edge of the cover fits. A little powdered
lime is placed in the crucible groove just before it is raised, so
that when the edges of the cover and crucible come together
THE MANUFACTURE OF SODIUM.
209
they form a tight joint, and at the same time will allow the
crucible to be lowered easily from the chamber when the ope-
ration is finished, to give place to another containing a fresh
charge. From the cover projects a slanting tube (see Fig. 18),
connected with the condenser. The condenser is provided
with a small opening at the further end to allow the escape of
hydrogen, and has also a rod fixed (as shown), by means of
which any obstruction which may form in the tube during dis-
FlG. 18.
tillation may be removed. After raising a crucible in its place
in the furnace, the hydrogen escaping from the condenser is
lighted, and serves to show by the size of the flame how the
operation is progressing in the crucible, the sodium actually
distilling soon after the crucible is in its place. The temper-
ature of the reduction and distillation has been found to be
about 823° C. The gas coming off during the first part of the
distillation has been analyzed and found to consist of pure
hydrogen. Analysis of the gas disengaged when the ope-
14
2IO ALUMINIUM.
ration was almost completed, gave as a result, hydrogen 95 per
cent., carbonic oxide 5 per cent. It has been found advisable
to use a little more 'carbide' than the reaction absolutely re-
quires, and this accounts for the presence of the small quantity
of carbonic oxide in the expelled gas, the free carbon acting
upon the carbonate formed by the reaction, thus giving off car-
bonic oxide and leaving a very small percentage of the residue
in the form of peroxide of sodium. This small amount of car-
bonic oxide rarely combines with any of the sodium in the
tube, and so the metal obtained in the condensers is pure, and
the tubes never become choked with the black compound. In
the preparation of potassium a little less ' carbide' is used than
the reaction requires ; thus no carbonic oxide is given off, and
all danger attached to the making of potassium is removed.
After the reduction and distillation the crucible is lowered from
the furnace and the contents poured out, leaving the crucible
ready to be recharged. The average analyses of the residues
show their composition to be as follows: —
Carbonate of soda 77 per cent.
Peroxide of sodium 2 "
Carbon 2 "
Iron 19 "
" The average weight of these residues from operating upon
charges of 15 lbs. caustic soda and 5^ lbs. of carbide is 16
lbs. These residues are treated either to produce pure crystal
lized carbonate of soda or caustic soda, and the iron is recov-
ered and used again with pitch in the formation of the ' car-
bide.' From this residue weighing 16 lbs., is obtained 13 lbs.
of anhydrous carbonate of soda, equivalent to 9.4 lbs. caustic
soda of 76 per cent.
" Operating upon charges as above mentioned the yield- has
been —
Sodium, actual 2.50 lbs. Theory 2.85 lbs.
Soda carbonate, actual 13.00 lbs. " 13.25 lbs.
" The average time of distillation in the large furnace has
THE MANUFACTURE OF SODIUM. 2 1 I
been i hour 30 minutes, and as the furnace is arranged for
three crucibles, 45 lbs. of caustic soda are treated every 90
minutes, producing 7^ lbs. of sodium and 39 lbs. of carbonate
of soda. The furnace is capable of treating 720 lbs. of caustic
soda daily, giving a yield in 24 hours of 120 lbs. of sodium and
624 lbs. of anhydrous carbonate of soda. The furnace is heated
by gas which is supplied by a Wilson Gas Producer, consuming
I cwt. of fuel per hour. The small furnace in which the
crucibles are first heated requires about J^ cwt. per hour. The
following estimate of cost, etc., is given from the actual running
of the furnace working with the above charges for 24 hours : —
£ ^. d.
720 lbs. of caustic soda @ ;^i i per ton 3 10 10
1 50 lbs. of " carbide " @ yd^d. per lb o 6 4
Labor I o o
Fuel o 17 o
Re-converting 624 lbs. of carbonate into caustic, at a cost
of about £^ per ton on the caustic produced, say ... I o o
Total 6 14 2
Deducting value of 475 lbs. of caustic recovered 2 6 8
Cost of 120 lbs. of sodium ^4 7 6
Cost per pound, 83^</.
" Regarding the item of cost relating to the damage caused
to the crucibles by the heat, this question has been very care-
fully gone into, some of the crucibles have been used upwards
of fifty times, and from present indications of their condition
there is no doubt that they can continue to be used at least 150
times more before they become unfit for further use. In con-
sidering 200 operations to be the life of a crucible, the item of
damage or wear and tear amounts to less than \d. per lb. on
the sodium produced; and if we take the furnace tear and wear
at the same rate of \d. per lb., we will see that the tear and
wear of plant is only one-twelfth of that incurred in the ordi-
nary propess. It is upon these facts that Mr. Castner bases
his claim to be able to produce sodium by Jiis- process upon
the large scale, at a cost of less than 15. per lb. The advan-
212 ALUMINIUM.
tages of this process will be apparent to any one at all familiar
with the manufacture of these metals as conducted heretofore.
The first and most important end gained is their cheap produc-
tion, and this is owing chiefly to the low heat at which the
metals are produced, the quickness of the operation, non- clog-
ging of the conveying tubes, and a very small waste of mate-
rials. The process furthermore admits of being carried on
upon a very large scale ; in fact, it is intended ultimately to in-
crease the size of the crucible so as to make the charges con-
sist of 50 lbs. of caustic soda. Crucibles of cast iron have
been found quite suitable, and it is intended in future, to use
crucibles made of this material in place of the more expensive
steel."
Immediately on the demonstration of this success, a company
was formed to unite Mr. Castner's sodium process with Mr.
Webster's improvements in the production of aluminium chlor-
ide. The Aluminium Co., Ltd., first appeared before the public
in June, 1887, and at the first meeting in the following Septem-
ber it was decided to build works at once. These were begun
at Oldbury, near Birmingham, and were in working operation
by the end of July, 1888. The furnaces here erected were
larger than the one just described, and altogether had a pro-
ducing capacity of nearly a ton of sodium a day. The follow-
ing details respecting this plant and its working are taken
mostly from an address delivered before the Society of Arts,
March 13, 1889, by Mr. William Anderson, and from a dis-
course at the Royal Institution, May 3, 1889, by Sir Henry
Roscoe, president of the company.
There are four large sodium furnaces, each holding five pots
or crucibles, and heated by gas, applied on the regenerative
principle. A platform about five feet above the floor allows
the workmen to attend to the condensers, while the lifts on
which the pots are placed sink level with the floor. The
crucibles used are egg-shaped, about 18 inches diameter at
their widest part and 24 inches high ; when joined to the cover
the whole apparatus is about 3 feet in height. The covers
THE MANUFACTURE OF SODIUM. 213
have vertical pipes passing through the top of the furnace,
forming a passage for the introduction of part of the charge,
and also a lateral pipe connecting with the condenser. The
whole cover is fixed immovably to the roof of the furnace and
is protected by brickwork from extreme heat ; but it can easily
be removed when necessary. The natural expansion of the
vessels is accommodated by the water pressure in the hydraulic
lifts on which the pots stand. When the lift is lowered and
sinks with the lower part of the crucible to the floor level, a
large pair of tongs mounted on wheels is run up, and catching
Fig. 19,
A CASTNER SODIUM FURNACE.
hold of the crucible by two projections on its sides, it is carried
away by two men to the dumping pits, on the edge of which it
is turned on its side, the liquid carbonate of soda and finely-
divided iron which form the residue are turned out, and the
inside is scraped clean from the opposite side of the pit, under
the protection of iron .shields. When clean inside and out, it
is lifted again by the truck and carried back to the furnace, re-
ceiving a fresh charge on its way. It is then put on the plat-
form and lifted into place, having still retained a good red heat.
It takes only i)^ to 2 minutes to remove and empty a crucible.
214 ALUMINIUM.
and only 6 to 8 minutes to draw, empty, recharge, and replace
the five crucibles in each furnace. The time occupied in re-
ducing a charge is one hour and ten minutes. It is thus seen
that one bank of crucibles yields 500 pounds of sodium in
twenty- four hours, the battery of four furnaces producing about
a ton in that time.
The shape of the condenser has been altogether changed.
Instead of the flat form used on the furnace at London (see
Fig. 18), which resembled the condenser used in the Deville
process, a peculiar pattern is used which is quite different. It
consists in a tube-shaped cast-iron vessel S inches in diameter,
nearly 3 feet long over all, and having a slight bend upwards at
a point about 20 inches from the end. At this bend is a small
opening in the bottom, which can be kept closed by a rod drop-
ping into it; this rod, passing through a tight- fitting hole
above, can be raised or lowered from outside. Thus the
sodium can either run out continually into small pots placed
beneath the opening or can be allowed to collect in the con-
denser until several pounds are present, then a small potful run
out at once, by simply lifting the iron rod. The outer end of
the condenser is provided with a lid, hinged above, which can
be thrown back out of the way when required. This lid also
contains a small peep-hole covered with mica. In the top of
the condenser just before the end is a small hole through
which the hydrogen aud carbonic oxide gases escape when the
end is closed, burning with the yellow sodium flame. The
bend in the condenser is not acute enough to prevent a bar be-
ing thrust through the end right into the outlet tube projecting
from the furnace, thus allowing the whole passage to be cleaned
out should it become choked up. Previous to drawing the
crucibles from the furnace for the purpose of emptying them
and recharging, the small pots containing the metal distilled
from one charge are removed and empty ones put in their
place. Those removed each contain on an average about 6 lbs.
of sodium, or 30 lbs. from the whole furnace. When sufficiently
cool, petroleum is poured on top of the metal in the pots, and
THE MANUFACTURE OF SODIUM. 21 S
they are -vvheeled on a truck to the sodium casting shop, where
the sodium is melted in large pots heated by oil baths and cast
either into large bars ready to be used for making aluminium
or into smaller sticks to be sold. The sodium is preserved
under an oil such as petroleum, which does not contain oxygen
in its composition, and the greatest, care is taken to protect it
from water.
Special care is taken to keep the temperature of the furnace
at about iOOO° C, and the gas and air-valves are carefully re-
gulated so as to maintain as even a temperature as possible.
The covers remain in the furnace from Sunday night to Satur-
day afternoon, and the crucibles are kept in use till worn out,
when new ones, previously heated red-hot, are substituted
without interrupting the general running of the furnace. These
bottom halves of the crucibles are the only part of the plant
liable to exceptional wear and tear, and their durability is found
to depend very much on the soundness of the casting, because
any pores or defects are rapidly eaten into and the pot de-
stroyed. The average duration of each crucible is now 750
lbs. of sodium, or 125 charges.
Apropos of the reaction involved in the reduction, it has
probably been observed that Mr. MacTear proposes a different
formula from that suggested by Mr. Castner. Mr. Weldon re-
marked that when a mixture of sodium carbonate and carbon
was heated the carbon did not directly reduce the soda, but at
a high temperature the mixture gives off vapors of oxide of
sodium (Na^O) part of which dissociates into free oxygen and
sodium vapor; as soon as this dissociation takes place the
carbon takes up the oxygen, forming carbonic oxide, and thus,
by preventing the recombination of the sodium and oxygen,
leaves free sodium vapors.
Dr. Kosman, speaking in " Stahl und Eisen," January, 1889,
on Castner's process, gives the following explanation of the re-
actions taking place : —
Ten kilos of caustic soda and 5 kilos of carbide (containing
1.5 kilos of carbon) give the following reaction:
2l6 ALUMINIUM.
4NaOH + FeCj = Na^COs + Fe + 4H + CO + 2Na,
and half the sodium in the mixture is obtained.
Ten kilos of caustic soda and 10 kilos of carbide (containing
3 kilos of carbon) give this reaction —
zNaOH + FeQ = NaCO + Fe + 2H + CO + Na,
and half the sodium in the mixture is again obtained.
If 20 kilos of caustic soda and 15 kilos of carbide are mixed,
both the above reactions take place ; but if the ignition is con-
tinued, the sodium carboxyd (NaCO) reacts on the sodium
carbonate according to the reaction —
Na^COs + NaCO = sNa + 2CO2,
and the entire reaction may be represented by
sNaOH + FeC^ = sNa + Fe + 3 H + CO -h CO,,
and all the sodium in the mixture is obtained.
This is the reaction first proposed by Mr. Castner (see p.
206), and the proportions indicated by it gave him the largest
return of sodium. Mr. MacTear, however, states that the re-
action which takes place is conditioned largely by the tempera-
ture, and that at 1000° C. it is probably to be represented by
6NaOH -I- FeCj = 2Na2C03 + 6H -F Fe + zNa,
which is essentially the same as that given by Sir Henry Ros-
coe in his discourse, viz : —
3NaOH + C = Na.CO, + 3H. + Na.
This reaction would require 18^ lbs. of carbide to 50 lbs. of
caustic soda, and since the sodium carbonate is easily converted
back into caustic by treatment with lime, the production of so
much carbonate is offset by the ease with which the reaction
takes place, and the added advantage that the gas evolved with
the sodium is solely hydrogen, thus allowing the reduction to
THE MANUFACTURE OF SODIUM. 217
proceed in an atmosphere of that gas, and reducing the pro-
duction of the usual deleterious sodium carbides to a minimum.
A further discussion of this subject will come up in consider-
ing Netto's process.
Netto's Process (1887).
Dr. Curt Netto, of Dresden, took out patents in several
Eurupean countries,* which were transferred to and operated
by the AlHance Aluminium Company, of London (see p. 31).
The process is continuous, and is based on the partial reduc-
tion of caustic soda by carbon. Dr. Netto observes that car-
bon will reduce caustic soda at first at a red heat, but a white
heat is necessary to finish the reduction, the explanation being
that the reaction is at first —
4NaOH + C = Na^COa-l- 2H, -t- CO + Na„
and that the carbonate is only reduced at a white heat. To
avoid any high temperature, the first reaction only is made use
of, the carbonate being removed and fresh caustic supplied
continuously, and without interrupting the operation or admit-
ting air into the retort in which the reduction takes place.
A vertical cast-iron retort, protected by fire-clay coating, is
surrounded by flues. The flame after heating the retort passes
under an iron pot in which the caustic soda is kept melted, and
situated just above the top of the retort. This pot has an out-
let tube controlled by a stop-cock, by which the caustic may
be discharged into a funnel with syphon-shaped stem fastened
into the top of the retort. There is also a syphon-shaped out-
let at the bottom of the retort, through which the molten so-
dium carbonate and bits of carbon pass. A hole with tight lid
in the upper cover is provided for charging charcoal. A tube
passes out just beneath the upper cover, connecting with a
large condenser of the shape used by Deville (see Fig. 20).
In operating, the retort is heated to bright redness, filled one-
third with best wood charcoal, and then . molten caustic soda
♦German patent (D. R. P.) 45105; English patent, October 26, 1887, No. 14602.
2l8
ALUMINIUM.
tapped from the melting-pot into the funnel, the feed being so
regulated that the funnel is kept full and the retort closed.
The lower opening is kept closed until enough sodium carbon-
ate has accumulated to lock the syphon passage air tight.
When after several hours' working the charcoal is almost all
used up, the supply of caustic soda is shut off for a time and
Fig. 20.
the retort recharged through the opening in the upper lid,
when the operation goes on as before. The sodium carbonate
produced is easily purified from carbon by solution. Since
sodium vapor at a high temperature is very corrosive, all rivets
and screw joints must be avoided in making the retort. On
this account, the outlet tubes should be cast in one piece with
the retort.
THE MANUFACTURE OF SODIUM. 219
Both Netto's process and Castner's were in use for a con-
siderable time ( 1 888-1 891), and produced sodium in large
quantities and cheaply. With the advent of the cheaper elec-
trolytic methods of producing aluminium, the sodium methods
were put to a sharp struggle for existence. The Alliance Alu-
minium Company, working the Netto process, soon gave up
the fight. The Aluminium Company, Limited, working Cast-
ner's process, were enabled to continue making aluminium for
some time longer by an invention of Mr. Castner's to produce
sodium electrolytically. This process is still being used, but
the sodium produced is used for various other purposes than
making aluminium, the extraordinary cheapness of the electro-
lytic processes rendering competition impossible.
Reduction of Sodium Compounds by Electricity.
The decomposition of fused sodium chloride by the electric
current seems to promise the economic production of sodium,
for not only is this metal formed, but chlorine is obtained as a
by-product, its value reducing very much the cost of the
operation.
P. JablochofF has devised the following apparatus for decom-
posing sodium or potassium chlorides.* (Fig 21.)
The arrangement is easily understood. The salt to be de-
composed is fed in by the funnel into the kettle heated by a fire
beneath. The positive pole evolves chlorine gas, and the
negative pole evolves vapor of the metal, for, as the salt is
melted, the heat is sufficient to vaporize the metal liberated.
The gas escapes through one tube and the metallic vapor by
the other. The vapor is led into a condenser and solidified.
Prof. A. J. Rogers, of Milwaukee, Wis., has made a number
of attempts to reduce sodium compounds electrolytically, using
as a cathode a bath of molten lead and producing an alloy of
lead and sodium which he makes use of for the reduction of
aluminium compounds. Although these attempts are hardly
* Mierzinski.
220
ALUMINIUM.
past the experimental stage, yet the record of the results ob-
tained may very probably be interesting and valuable to other
investigators in this line.
Prof. Rogers reasons that from the known heat of combina-
FlG. 21.
unvrm |>T«"
tion of sodium and chlorine (4247 calories per kilo of sodium)
there is enough potential energy in a pound of coal to separate
nearly two pounds of sodium, if any mode of applying the com-
bustion of the coal to this end without loss could be devised.
If, however, this energy is converted into mechanical work, this
again into electrical energy, and this latter used to decompose
sodium chloride, we can easily compute the amount of coal to
be used in a steam boiler to produce a given amount of sodium
by electrolysis. Now, if the electric current could be applied
without loss in decomposing sodium chloride, i electric horse-
power (746 Watts) would produce about 8 lbs. of sodium in
24 hours. But as in practice one mechanical horse-power ap-
plied to a dynamo yields only 80 or 90 per cent, of an electric
horse-power, and as about 4 lbs. of coal are used per indicated
THE MANUFACTURE OF SODIUM. 221
horse-power per hour, from 105 to 120 lbs. of coal would be
required per day to produce this result, or about 15 lbs. per lb.
of sodium. Since, however, there is a transfer resistance in the
passage of the electric current through the molten electrolyte,
more than this will be required, in proportion to the amount of
current thus absorbed.
The temperature of fusion of sodium chloride is given by
Carnelly as Tj6° C, but Prof. Rogers remarks that the fusing
point may be lowered considerably by the presence of other
salts ; for instance, it melts about 200° lower if a small amount
of calcium chloride or potassium chloride is present. We will
quote the results of some experiments as given by Prof.
Rogers.*
"The following results were obtained among many others by
using a Grove battery, a Battersea crucible to hold the sodium
chloride, a carbon anode and an iron cathode terminating in a
tube of lime placed in the melted salt. As soon as metallic
sodium escaped and burnt at the surface of the liquid the cur-
rent was stopped. A little sodium was oxidized, but a consid-
erable amount was found in the tube in the metallic state. In
six experiments the amount of sodium obtained was from 50 to
85 per cent, of the theoretical amount, averaging 65 per cent.
It thus seemed that, with suitable apparatus, from 5 to 6 lbs. of
sodium could be obtained in 24 hours per electric horse-power.
Thus, if there were no practical difficulties in the construction
of the crucibles and other apparatus involved, nor in working
continuously on a large scale, the metal could be obtained at
small cost. Various forms of crucibles were used and attempts
made to distil the metal when formed at the negative electrode
(sodium volatilizing at about 900° C), but the sodium vapor
carries with it a large amount of sodium chloride as vapor, and
the distillation is attended with difficulty.
" During the last three years I have experimented on the
reduction of sodium chloride, using molten negative electrodes
and especially lead. Lead, tin, zinc, cadmium and antimony
* Proceedings of the Wisconsin Natural History Society, April, 1889.
222 ALUMINIUM.
all readily .alloy, with sodium, a large part of which can be re-
covered from the alloys by distillation in an iron crucible. They
can be heated to a higher temperature than pure sodium in
acid crucibles without the sodium attacking the crucible. In
the following experiments a dynamo machine was used to sup-
ply the current.
"Experiment i. A current averaging 72 amperes and 33
volts was passed through molten sodium chloride contained in
two crucibles arranged in series, for two hours. Each con-
tained 30 lbs. of salt; in the first was put 104 grammes of tin,
in the second 470 grammes of lead, each serving as cathode,
and connection being made through the bottom of the crucible.
A carbon anode passed through the cover and extended to
within three inches of the molten cathode. The crucible con-
taining the tin was nearer the fire and consequently hotter, and
had an average potential across the electrodes of 12 volts,
while that containing the lead cathode was 21 volts. When at
the end of two hours the carbons were removed and the cru-
cibles cooled and broken open, the lead alloy was found to
contain 96 grammes of sodium, or 17 per cent. There was
about 90 grammes of sodium found in the tin alloy, or between
45 and 50 per cent. Both these alloys rapidly oxidized in the
air, and when thrown into water the action was very energetic,
in the case of the tin alloy the liberated hydrogen being ignited,
and after the reaction the metals were found at the bottom of
the vessel in a finely divided state. Both these alloys reduce
cryolite or aluminium chloride."
In Prof. Rogers' further experiments cryoHte was added to
the bath, so that sodium was produced and aluminium formed
in one operation. (See under "Electrolytic Processes,"
Chap. XI.)
L. Grabau, of the " Aluminium Werke zu Trotha," has
made the following observations on the electrolysis of molten
sodium chloride. When the melted, salt is subjected to the
electric current, the resistance of the bath quickly rises and it
becomes almost inipossible to force the current through, This
THE MANUFACTURE OF SODIUM. 223
is probably due to the formation of a non-conducting sub-
chloride. The formation of this salt can be prevented by the
addition of some potassium chloride and the chloride of an
alkaHne-earth metal to the bath. In his patents,* Grabau
recommends the use of a mixture of sodium, potassium and
strontium chlorides, in the proportion of 88 sodium chloride,
112 potassium chloride, and 159 strontium chloride. With this
mixture, Grabau claims to obtain almost pure sodium, contain-
ing only about 3 per cent, of potassium and no trace of
strontium, while at the same time 95 per cent, of the metal
which the current should theoretically give is obtained. For
all the purposes to which sodium is now applied the presence of
the potassium is not in the least prejudicial. Borchers sub-
stantiates the fact that from a mixture of potassium and sodium
chlorides, which is very fluid, only sodium is liberated by the
current if it is not too strong and if the sodium chloride de-
composed is at once replaced. For carrying on his process,
Grabau uses the apparatus shown in Fig. 22. The positive
poles are carbon rods (C), the negative an iron pipe E, slit in
its lower part and surrounded by a bell-shaped porcelain cover
B. As the molten sodium is lighter than the bath material, it
rises into the pipe £ and passes away through the branch a into
a condenser where it collects under petroleum. The screw H
can be turned downwards to clean out the tube E in case it
stops up. It is intended that the vessel should be heated by
hot gases passing through the flues G G, and its temperature so
regulated that the sodium passes off in the liquid state. The
chlorine generated passes off by the tube d. In order to pre-
vent the corrosion of the cover B, Grabau has even con-
structed an apparatus in which it contained an iron lining and
was water-cooled.
The method now used by Castner .consists in electrolyzing
molten caustic soda at the lowest possible temperature. Pure
caustic soda melts below redness, and if kept at a temperature
♦German Patents (D. R. P.) Nos. 51898 and 56230 (1890).
224
ALUMINIUM.
not more than 20° above its melting point (310° C), it can be
easily and continuously electrolyzed. Arrangements must
therefore be provided for keeping the temperature of the bath
very constant, and for removing the sodium quickly from the
bath in order to prevent loss by corrosion. The apparatus
consists of an iron crucible, embedded in brickwork, in which
Fig. 22.
the caustic soda is melted by the heat of a circular gas burner
surrounding the pot (Fig. 23). The negative electrode passes
up through the bottom of the pot, the space between it and the
sides of the hole being allowed to fill up with solid caustic. A
tubular sleeve of iron descends from the cover and envelopes
the top of this electrode. Outside of this are the positive elec-
trodes. An opening is provided in the cover for the escape of
THE MANUFACTURE OF SODIUM.
225
gas and introduction of a thermometer. In operation, the heat
caused by the passage of the current is sufificient to keep the
bath melted. The free sodium floats on the surface of the bath
inside the iron sleeve surrounding the negative electrode, and
is skimmed off with a small ladle having fine perforations. The
operation is continuous, and afifords sodium at a cost probably
not greater than 15 cents per pound.
IS
CHAPTER VIII.
THE REDUCTION OF ALUMINIUM COMPOUNDS FROM THE
STANDPOINT OF THERMAL CHEMISTRY.
The branch of chemical science called thermal chemistry may
be said to be yet in its infancy. Although an immense mass
of thermal data has been accumulated, yet the era of great
generalizations in this subject has not yet been reached ; and
although we know with a fair degree of accuracy the heat of
combination of thousands of chemical compounds, including
nearly all the common ones, yet the proper way to use these
data in predicting the possibility of any proposed reaction re-
mains almost unknown. The principal barriers in the way are
two: 1st, the unknown quantities entering into almost every
chemical reaetion thermally considered, i. e., the heat of com-
bination of elementary atoms to form molecules of the ele-
ments ; 2d, the uncertainty as regards the critical temperature
at which a given exchange of atoms and consequent reaction
will take place. We will explain what is meant by these state-
ments.
To illustrate, let us consider the case of hydrogen uniting
with oxygen to form water according to the formula —
2(H— H) -I- (0= 0)= 2H,0
where (H — H) and (O ^ O) represent respectively molecules
of hydrogen and oxygen. Now, as i kilo of hydrogen unites
with 8 of oxygen to form 9 of water, setting free 34,462 units
of heat (calories), if we take the atomic weights in the above
reaction as representing kilos, we shall have the thermal value
of the reaction 4 X 34,462 = -|- 137,848 calories. But this'
quantity is evidently the algebraic sum of the heat evolved in
(226)
REDUCTION OF ALUMINIUM COMPOUNDS. 22/
the union of 4 kilos of hydrogen atoms with 32 kilos of oxygen
atoms, and the heat absorbed in decomposing 4 kilos of hydro-
gen gas into atoms! and 32 kilos of oxygen gas into atoms.
These two latter quantities are unknown, though a few chem-
ists have concluded from studies on this question that they are
probably very large. It has been calculated that the reaction
H -|- H = (H — H) sets free 240,000 calories,
and 0 4-0^ (O = O) sets free 147,200 calories ;
If these numbers are approximately true, then
4H + 20^ 2H2O would set free about 773,000 calories.
If these quantities are really anything like so large, and if
they are at sometime determined with precision, thermo-chem-
ical principles and conclusions will be greatly modified. Mean-
while, predictions based on the data we have, lose all possibility
of certainty, and so we need to keep in mind in our further
discussion that our deductions at the best are only probabil-
ities. Further, suppose that we mix i kilo of hydrogen gas
and 8 kilos of oxygen gas, put them in a tight vessel and keep
them at the ordinary temperature. No reaction will take place
in any length of time, even though 34,462 calories would be
set free thereby. The explanation of this is that the atoms of
hydrogen and oxygen are so firmly bound to each other in the
molecules, that the dissimilar atoms have not strength of afiSnity
sufiScient to break away in order to combine. It is well known
that a spark only is necessary to cause an explosive combina-
tion of the gases under the above conditions, the temperature
of the spark expanding the gases coming in contact with it,
causing the atoms to swing with more freedom in the molecules ;
and as soon as two atoms of hydrogen come within the .sphere
of attraction of an atom of oxygen and form a molecule of
water, the heat liberated is immediately communicated to the
adjacent atoms, and almost instantaneously the entire gases
have combined. The same principle undoubtedly holds true
228 ALUMINIUM.
in cases of reduction. Carbon may be mixed with litharge
and the mixture left in the cold forever without reacting, but at
a certain temperature the carbon will abstract the oxygen. The
temperatures at which reactions of this nature will take place
are often determined experimentally.
There are other points which are somewhat indeterminate in
these discussions, such as the influence of the relative masses
of the reacting bodies, their physical states, i. e., solid, liquid
or gaseous, also the influence of the physical conditions favor-
ing the formation of a certain compound ; but the nature of the
subject and the meagreness of data in the particular pheno-
menon of reduction, render it inexpedient if not impracticable
to take these points into consideration.
Starting with the above remarks in view, we will consider the
heat generated by the combination of aluminium with certain
other elements, as has been determined experimentally, and
study, from a comparison with the corresponding thermal data
for other elements, what possibilities are shown for reducing
these aluminium compounds.
The heat generated by the combination of aluminium with
the different elements is given as follows : the first column giv-
ing the heat developed by 54 kilos of aluminium (representing
AI2), and the second the heat per atomic weight of the other
element, e. g., per 16 kilos of oxygen.
Element. Compound. Calories. Calorie.s. Authority.
Oxygen * Al^Oj 391,600 130,500 Berthelot.
392,600 130,900 Bailie & F^ry.
Fluorine 2AIF3 552,000 92,000 Berthelot.
Chlorine 2AICI3 321,960 53,66o Thomsen.
Bromine 2AlBr3 239,440 39,900 "
Iodine 2AU3 140,780 23,460 "
Sulphur AI2S3 124,400 41,467 Sabatier.
* Berthelot's number represented the formation of the hydrated oxide, AIJO3.3H2O,
and, for want of knowing the heat of hydration, has been generally used as the heat
of formation of AljOj. Recently, J. B. Bailie and C. F4ry (Ann. de Chim. et de
Phys., June, 1889, p. 250) have, by oxidizing aluminium amalgam, obtained the above
figure for the heat of formation of AI2O3, and determined that the beat of hydration
is 3000 calories, which would make the heat of formation of the hydrated oxide
395,600.
REDUCTION OF ALUMINIUM COMPOUNDS. 229
Let US consider the theoretical aspect of the reduction of
alumina. The heat given out by other elements or com-
pounds which unite energetically with oxygen is as follows, the
quantity given being that developed by combination with 16
kilos (representing one atomic weight) of oxygen.
Element. Compound. Calories.
AlTiminlum AljOj 130,500
Sodium Na.p 99, 760
Potassium Kfi 100,000 ( ?)
Barium BaO 124,240
Strontium SrO 1 28,440
Calcium CaO 130,930
Magnesium MgO 145,860
Manganese MnO 95,ooo ( ?)
Silicon SiOj 1 10,000
Zinc ZnO 85,430
Iron FejOj 63,700
Lead PbO 50,300
Copper CuO 37>i6o
" CU2O 40,810
Sulphur SO2 35.540
Hydrogen H^O 68,360
Carbon CO 29,000
" COj 48,480
Carbonic anhydride CO^ 67,960
Potassium cyanide KCyO 72,000
On inspecting this list we find magnesium to be the only metal
surpassing aluminium, while calcium is about the same. This
would indicate that the reaction
AlA + 3Mg = Al, + 3MgO
would, if it were possible to bring the alumina and magnesium
in the proper conditions for reacting, develop about
(145,860 — 130,500) X 3 = 46,080 calories,
and points to the possibility of reducing alumina by nascent,
molten, or vaporized magnesium, under certain conditions. In
fact, since this paragraph was first written, in 1890, Dr. Clemens
Winkler has succeeded in performing the reduction in part.*
* Berliner Berichte, 1890, p. 772.
230 ALUMINIUM.
He found that when alumina was heated with magnesium pow-
der in a current of hydrogen, a nearly black powder resulted,
containing a lower oxide of aluminium, AlO, the reaction
being
2AI2O, + Mg = MgO.AljO, + 2AIO ;
the magnesia formed uniting with alumina to form an alum-
inate.
We notice further the fact that sodium or potassium could
not reduce alumina without heat being absorbed in large
quantity, and it is interesting to remember that some of the
first attempts at isolating aluminium by using potassium were
made on alumina, and were unsuccessful, so that it is practi-
cally acknowledged that while these metals easily reduce other
aluminium compounds (according to reactions which are ther-
mally possible, as we shall see later on) yet they cannot reduce
alumina, under any conditions so far tried.
When we consider the case of reduction by the ordinary re-
ducing agents, hydrogen, carbon, or potassium cyanide, we are
confronted in every case with large negative quantities of heat,
i. e., deficits of heat. So large do these quantities appear that
it is very small wonder that the impossibility of these reduc-
tions occurring under any conditions has been strongly affirmed,
For instance
Al203-f-6H=AU-|-3H,0
would require
(130,500 — 68,360) X 3 = 186,420 calories.
AI2O3 + 3C =Alj -I-3CO 304,500 calories.
AI2O3 + i>^C = AI2 -h ii^COa 246,060 calories.
Al,03 -I- 3KCy = Al, + 3KCyO 175,500 calories.
AlA +3CO =h\ + 7,C0, 187,620 calories.
The above quantities represent the differences between the
heats of formation of alumina and the product of the reduc-
tion, assuming the reaction to take place at ordinary temper-
atures. At high temperatures these heats of formation are in
REDUCTION OF ALUMINIUM COMPOUNDS. 23 1
general less than they would be at low heats, and if the heat of
formation of alumina decreases faster than .the heat of combi-
nation of the reducing agent with oxygen, the dififerences noted
above would be less and the reaction easier to produce. This
must be what actually takes place. For instance, at the heat
of an electric furnace, say 2500° to 3000°C., molten alumina
is reduced by carbon present in large quantity, that is, the dif-
ference beiween the heats of formation of AI2O3 and 3 CO has
become so small that the reaction takes place. Similarly,
Warren has recently reduced alumina by heating it in a lime
tube by an oxy-hydrogen blow-pipe, passing hydrogen through
the tube. We here have a reaction which is negative by 186,-
000 calories at ordinary temperatures, taking place at a tem-
perature probably not over 2000°C.
The conditions which render the carrying out of these diffi-
cult reductions possible are therefore :
1 . A high temperature, which weakens the heat of formation
of alumina.
2. An excess of the reducing agent, which is thus assisted
simply by the overpowering influence of its mass.
3. Fluidity of the substance to be reduced.
4. Intimate contact with the reducing agent.
5. Favorable conditions for the formation and removal of the
gaseous products of the reduction.
Concerning these, I would remark that the fluidity of the sub-
stance to be reduced may be attained by other means than a
high temperature. The alumina may, for instance, be liquefied
by solution in a bath of molten cryolite. If we dissolve it in
molten caustic soda we get a combination of alumina and soda
which will remain fluid if too much alumina is not added.
Such fluidity also allows much more intimate contact with the
reducing agent if it is a solid. . If the reducing agent is a gas,
most intimate contact is obtalined by finely pulverizing the alu-
mina. If the reducing agent is a solid and the product of the
reduction would be a gas, its formation would be accel-
erated by reducing the pressure in the apparatus. In other
232
ALUMINIUM.
words, a partial vacuum would undoubtedly aid in bringing
about the reduction, and would help to keep the aluminium in
the metallic state by removing quickly the product of reduction
and so preventing re-oxidation. I have no hesitation in affirm-
ing that since we now know that carbon does reduce molten
alumina below 3000°, and hydrogen reduces solid alumina at
2000°, the application of correct principles by intelligent inves-
tigators, with properly constructed apparatus, would undoubt-
edly result in discovering methods of producing the same reac-
tions at lower temperatures and on a larger scale. Whether
these methods of producing aluminium could compete with the
present electrolytic ones is another question, but it is certainly
interesting to mark the possibility of processes which some
future investigator may bring to commercial success.
As the basis of our discussion of the reduction of aluminium
chloride, bromide, or iodide, we give a table of heat developed
by the combination of some of the elements with one atomic
weight (in kilos) of each of these haloids.
Element.
Com-
pound.
Calories.
Com-
pound.
Calories.
Com-
pound.
53>66o
AlBrj
40,000
AII3
105,600
KBr
95.300
KI
97,690
NaBr
85,700
NaT
93.810
BaBr^
97.37°
SrBr^
85,000
92,270
CaBr^
78,900
84,910
70,400
75.5°°
56,000
f 5o,6oot
1 48,600*
jZnBr,
f43.ioot
] 40,640t
I 37.500*
[znP
41,380
PbBrj
32,200
Pblj
41.275
H&Br,
34.150
Hg,I,
40,400
41,000
FeBrj
24,000
Felj
32.87s
Cu^Br^
25,000
C%I,
22,000
HBt
8,400
HI
Calories.
Aluminium
Potassium . .
Sodium
Lithium ....
Barium ....
Strontium . .
Calcium ....
Magnesium.
Manganese .
Zinc
Lead
Mercury . . . •
Tin
Iron
Copper . . . .
Hydrogen. .
AlCl,
KCl
NaCl
LiCl
BaClj
SrClj
CaClj
MgCL,
MnCL,
ZnClj
PbCl^
Hg,Cl,
SnCL,
FeCl.,
CuoCl.^
HCl
23,460
80,100
69,000
f 30,coot
■j 26,600
(. 24,500
20,000
24,200
8,ooot
16,000
— 6,000
*Thomsen. t Andrews. J Jahresbericht der Chemie, 1878, p. 102,
On inspecting this table we notice that, in general, all the
REDUCTION OF ALUMINIUM COMPOUNDS. 233
metals down to zinc develop more heat in forming chlorides, and
very probably also in forming bromides and iodides, A re-
action, then, between aluminium chloride and any of these
metals, forming aluminium and a chloride of the metal, would
be exothermic, which means, generally speaking, that if alu-
minium chloride and any one of these metals were heated to-
gether to the critical point at which the reaction could begin,
the reaction would then proceed of itself, being continued by the
heat given out by the first portions which reacted. Zinc seems
to lie on the border line, and the evidence as to whether zinc
will practically reduce these aluminium compounds is still con-
tradictory, as may be seen by examining the paragraphs under
" Reduction by Zinc." (Chap. XII.)
Of the first six metals mentioned in the table after aluminium,
only potassium and sodium are practically available. The re-
action
AlCl3 + 3K = AH-3KCl develops 155,820 cal.
AlCls-F 3Na = Al-f- 3NaCl develops 132,090 cal.
and the result of this strong disengagement of heat is seen
when, on warming these ingredients together, the reaction once
commenced at a single spot all external heat can be cut off, and
the resulting fusion will become almost white hot with the heat
developed. In fact, the heat developed in the second reaction
would theoretically be sufficient to heat the aluminium and
sodium chloride produced to a temperature between 3000° and
4000°.
Magnesia should act in a similar manner, though not so vio-
lently, since
2AlCl3 + 3Mg=Al2 + 3MgCl2 develops 131,000 cal.
And manganese possibly also, since
2AICI3 + 3Mn = Ala -f- 3MnCl develops 14,040 cal.
The reduction of aluminium chloride, bromide, or iodide by
hydrogen is thermally strongly negative, which would indicate
a very small possibility of the conditions ever being arranged so
234 AXUMINIUM.
as to render the reaction possible. For instance, taking the
most probable case,
AICI3 + 3H = Al + 3HCI requires 94,980 calories.
The only probable substitutes for sodium in reducing alumin-
ium chloride are thus seen to be magnesium (whose cost will
probably be always greater than that of aluminium), manganese
(which may sometime be used in the form of ferro-manganese
for producing ferro-aluminium), and zinc (whose successful
application to this purpose would be a most promising advance
in the metallurgy of aluminium).
In 1886 Moissan isolated fluorine, and in 1889 he and Berthe-
lot measured the heat of formation of hydrofluoric acid. With
this datum, it became possible to calculate a table of the heat
of formation of the fluorides.* These can now be given as
follows, stating the heat evolved by combination with one
atomic weight (19 kilos) of fluorine.
Element. Compound, Heat evolved.
Potassium KF 1 10,000
Sodium NaF 109,700
Barium BaF^ 112,000
Strontium SrFj 112,000
Calcium CaF, 108,000
Magnesium MgFj 105,000
Aluminium AIF3 92,000
Manganese MnFj 72,000
Zinc ZnFg 69,000
Cadmium CdF^ 61,000
Iron FeF^ 63,000
Cobalt C0F2 60,000
Nickel NiFj 59,500
Copper CuFj 44,000
Silver AgF 25,500
Hydrogen HF (gas) 37,6oo
" " (in solution) 49,400
It follows from an inspection of these quantities that the
fluorides are stronger compounds than either the oxides, chlor-
ides, bromides or iodides. It is also seen that aluminium
* See a paper on this subject, by the author, in the Journal of the Franklin Insti-
tute, June, 1891.
REDUCTION OF ALUMINIUM COMPOUNDS. 235
stands in the same relative position as in the chlorides, except
that it is here stronger than manganese or zinc. It follows that
only sodium, potassium or magnesium of the available metals
wilU reduce aluminium fluoride. For such reductions the latter
must be liquefied by mixture with a fusible salt not acted on by
the reducing agent. Thus, we* would have
2AIF3 + 6Na= 6NaF+ 2AI, evolving 106,200 calories.
2A1F3 + 3Mg = 3MgF2 + 2AI, evolving 78,000 calories.
The reaction with zinc would absorb heat as follows :
2AIF3 + 2Zn= 2ZnF2 + 2 Al, absorbing 138,000 calories.
While the first two reactions take place easily, at a red heat,
the latter is nearly impracticable. The writer brought zinc into
contact with highly heated cryolite (AlFj.sNaF), and obtained
0.6 per cent, of aluminium in the zinc* The temperature was
a bright red, and this small amount of reduction shows that an
excess of zinc at a high temperature will to a small extent over-
come the affinity of aluminium for fluorine. Manganese in the
form of ferro-manganese, might take up even a larger percent-
age of aluminium than the above, yet no substantial amount of
reduction can be looked for from these elements.
In order to discuss the thermal relations of aluminium sul-
phide, we will make use of the following data, the heat devel-
oped being per atomic weight (32 kilos) of sulphur combining:
Element. Compound. Calories.
Alumlnitiin AI283 41,467
Potassium KjS 103,700
Sodium Na^S 88,200
Calcium CaS 92,000
Strontium SrS 99,200
Magnesium MgS 79,600
Manganese MnS 46,400
Zinc ZnS 41.326
Iron FeS 23,576
Copper Cu^S 20,270
Lead • PbS 20,430
Hydrogen HjS 4>740
Carbon CSj —14,500
* See details in Chapter XII.
236 ALUMINIUM.
These figures point to the easy reduction of aluminium sul-
phide by potassium, sOdium, or magnesium, and its possible
reduction by manganese and zinc. The other metals would
require exceptional conditions, perhaps, of temperature, for
their action. It is interesting to note that two observers have
determined from the deposition -of the metals from solution by
hydrogen sulphide, that the order of the afifiinity of the metals
for sulphur is first the alkaline metals, then the others in the
following order: copper, lead, zinc, iron, manganese, and then
aluminium and magnesium — with the remark that the affiinities
of the latter two for sulphur appear quite insignificant. The
explanation of this difference is that the metals last mentioned
form sulphides which are not stable in water, but are immedi-
ately decomposed according to the reaction
3 AI2S3 + 3 H2O = AI2O3 + 3H2S, evolving 77,840 calories,
while the alumina produced is immediately soluble in the weak
acid solution and at once disappears. It follows that these ele-
ments are not precipitated as easily from solution as those
whose sulphides are not thus decomposed by water.
The reduction of aluminium sulphide by copper, tin and iron
is in a measure possible when the operation is conducted at a
high temperature and there is an excess of reducing metal
present. Under these conditions, a part of the aluminium sul-
phide is reduced and an alloy formed, but such reactions can-
not approach in completeness those reactions which are
strongly endothermic. The reduction by hydrogen is seen to
be highly improbable, and by carbon still more so.
The question of reducing aluminium compounds by the use of
electricity is a very different question. Looked at as a reduc-
ing or decomposing agent, the electric current is almighty. A
current with a tension of i volt will decompose any fluoride,
chloride, bromide or iodide whose heat of combination with one
atom weight of fluorine is less than 23,000 calories ; at a tension
of two volts, any less than 46,000 calories ; and therefore at a
tension of five volts would decompose the strongest of any of
REDUCTION OF ALUMINIUM COMPOUNDS. 237
these salts. Such a current only means half a dozen ordinary
copper sulphate batteries connected in tension. For oxides
and sulphides, the heat of combination with one-half an atomic
weight must be used, which quantity is equal in combining
power to one whole atomic weight of the above elements, and
then the same rule applies. We can thus calculate the voltage
required to decompose the following anhydrous molten com-
pounds—
» Element. Fluoride. Chloride. Oxide. Sulphide.
Potassium 4.8 4.6 2.2 2.3
Sodium 4.7 4.3 2.2 1 .9
Barium 4.9 4.3 2.7 2.2
Strontium 4.9 4.0 2.75 2.2
Calcium 4.7 3.7 2.85 2.0
Magnesium 4.6 3.3 3.2 1.7
Aluminiuin 4.0 2.3 2.8 0.9
Manganese 3.1 2.4 2.1 l.o
Zinc 3.0 2.3 1 .9 0.9
Iron 2.7 1.8 1.5 0.5
Nickel 2.5 1.6 1.3 0.4
Copper 1.9 1.4 0.9 0.4
Silver i.i 1.3 o.l o.i
Hydrogen 1.6 i.o 1.5 0.1
A critical comparison of these figures leads to some very in-
teresting conclusions. We notice, in the first place, that in the
fluorides there is a very sharp drop after aluminium ; in these
salts aluminium has closer resemblance to the alkaline earth
fluorides, while manganese and zinc resemble the ordinary
metals. In the chlorides, there is a sharp drop before alumin-
ium, leaving it in stronger resemblance to the zinc, manganese
and lower metallic salts. In the oxides, aluminium is again
classed with the alkaline earth metals, and sharply separated
from the lower metallic oxides. Attention is particularly called
to the irregularity of the alkaline metals, whose oxides are as
easily decomposed as those of the metals below aluminium.
This explains why we can reduce these alkaline metals more
easily by carbon than we can alumina, and yet we can use the
alkaline metal to react on a salt of aluminium and get metallic
238 ALUMINIUM.
aluminium. The high voltage required to decompose mag-
nesium oxide also explains the wonderful efficiency of mag-
nesium as a reducing a:gent when acting on the oxides. In the
list of sulphides, we again notice a sharp drop before alumin-
ium, leaving it in close correspondance with manganese and
zinc. The very low voltage required is also noticeable ; a
single Daniell cell should be able to produce decomposition.
Take a bath, for instance, in which alumina is being decom-
posed using a tension of 5 volts, of which 2.8 is absorbed in
decomposition and 2.2 in overcoming other resistances. If
aluminium sulphide were the material decomposed, assuming
other resistances the same as before, the total resistance of the
bath would be overcome by 3.1 volts; or, in other words, it
would require only 62 per cent, of the power to produce the
same weight of aluminium. The sulphide thus presents great
advantage in respect to ease of decomposition.
Next to the sulphide, the chloride is the easiest to decom-
pose, but both these salts are difficult to produce, and herein
lies their chief disadvantage.
It can be furthermore observed, that if we mix these various
salts into one bath, and use an electric current carefully regu-
lated as to tension, we can act on pne ingredient without dis-
turbing to any extent the others present. We could, for
instance, mix aluminium chloride with any fluoride down to
that of zinc, and by a tension of 2.5 volts or a little over sepa-
rate out only alumininum. We could mix alumina with any
fluoride or chloride above aluminium in the list, and get only
aluminium from the bath. The fact is, however, that alumina
is not dissolved by the chlorides, but only by the fluorides.
These latter are therefore available, and are the principal salts
used at present in the aluminium industry. Thus, in Hall's
process we have present in the bath
Alumina requiring 2.8 volts for decomposition.
Aluminiunl fluoride " 4.0 " "
Sodium '■ " 4.7 . " , •'
When the current is passed through such a mixture, and its
REDUCTION OF ALUMINIUM COMPOUNDS. 239
tension does not rise abnormally high,' the bath being kept sat-
urated with all the aluimina it can dissolve, the only ingredient
decomposed is the alumina.
In Minet's process there are present :
Alumina, requiring 2.8 volts.
Aluminium fluoride, " 4.0 "
Sodium fluoride, " 4^7 "
Sodium chloride, " 4.3 "
The minimum electro-motive force required to decompose
this bath at 900° is 2.4 volts; at 1100°, 2.17 volts. The elec-
tro-motive force of carbon burning to carbonic oxide at those
temperatures is, however, 0.65 volts, so that the voltage re-
required to decompose liquid alumina at these temperatures is
0.65 volts higher than the figure given. We therefore have
these data for the decomposition of alumina :
Voltage for
Temperature.
Decomposition.
Heat of Formation.
0°
2.82
392,600 (solid aluminium.)
0°
2.78
387,200 (liquid aluminium).
900°
3-05
424,600 (liquid aluminium).
1100°
2.82
392,600 (liquid aluminium).
The equation for the voltage required to decompose alumina
producing liquid aluminium is therefore :
V^ 2.78 + 0.00129 t — 0.00000128 1'',
and the heat required to decompose the molecule of alumina is
Q = 387,200+ 192 t — 0.1766 1^
This formula is extremely interesting from a thermo-chemi-
cal point of view in enabling us to calculate theoretically the
temperature at which hydrogen or carbon begins to reduce alu-
mina. The heat of formation of gaseous water ,at zero is accu-
rately known, and the experiments of Mallard and Le Chatelier
on the specific heats of hydrogen, oxygen and water vapor
enable us to calculate the heat of formation at any desired tern-
240 ALUMINIUM.
perature. From these data we calculate the heat of formation
of 3HjO to be represented by the formula:
Q = 174,300+ 7.71 t — 0.0072 t\
Now to find the temperature at which hydrogen gas would be-
gin to reduce alumina, we equate this formula with the one
given for the heat of the formation of alumina, and have
387,200 + 192 t — 0.1766 t''= 174,300+ 7.71 t— 0.0072 t''
from which
t = i785°C.
This will be the temperature at which the heat of formation
of 3H2O will be exactly equal to the heat of formation of Al^Oj,
and consequently immediately above this temperature reduc-
tion will begin if the physical conditions are favorable for the
reaction taking place.
On a similar principle we can calculate the temperature at
which carbon will begin to reduce aluminium, except that the
operation is more difficult because of the variable specific heat
of carbon. I have calculated from Weber's results that the heat
in carbon from zero to high temperatures may be expressed as
Q = o.5 t — 120.
Taking this quantity, in connection with the specific heats of
oxygen and carbonic oxide as determined by Mallard and Le
Chatelier at high temperatures, we have for the heat of forma-
tion of 3CO at any temperature t above 1000°, the expression
Q = 83.35s + 8.6472 t - 0.0009 t^
For finding the temperature at which reduction begins we have
387,200 + 192 t — 0.1716 t'' = 83,355 + 8.6472 t — 0.0009 ^^
from which
t = 1980°.
REDUCTION OF ALUMINIUM COMPOUNDS. 24 1
The temperatures above calculated appear much lower than
has heretofore been deemed possible, but they are supported by
experimental evidence ; viz., the reduction of alumina by
hydrogen performed by Warren, at a temperature which it is
hardly possible could have been higher than 2000° ; and the
production of pig-iron containing over i per cent, of aluminium
in a Pennsylvania blast furnace. The highest temperature at-
tained in this furnace, not of very modern construction, could
not have exceed 2000° C. (For details, see Chapter XII.)
If in place of free hydrogen gas or free carbon we use as a
reducing agent a combination of these two which gives out heat
in its dissociation into carbon and hydrogen, we would have a
more efficient reducing agent than if the constituents were used
separately. Such a compound is Acetylene, CjHj, which ab-
sorbs heat in its formation and therefore gives out heat in its
decomposition. At ordinary temperatures, Berthelot has found
that
C2 + H2 = C.2H.2 absorbs 5 1,500 calories.
We do not know exactly how this number varies with the tem-
perature, as we lack the specific heat of CJ-Ij, but we know that
it does not change very much. We would therefore have the
reduction equation as follows —
AI2O3 + C.,H2 = 2AI + 2CO -I- H,0
and the heat requirements as follows —
Reducing AljOa ■• 387,200 -|- 192.61— 0.17161'' (l)
Developed in forming 2CO 55.57° -f- S-76t — o.ooo6t'' (2)
" " « HjO 58,000-1- 2.571— 0.00251^ C3>
" " decomposing CijHj. 51,500 (4)
If we put (i) = (2) + (3) + (4) and solve for t, we obtain
the theoretical temperature at which Acetylene should begin to
reduce alumina as
t=-i87o°C.
This temperature, it will be observed, is not so low as that
16
242 ALUMINIUM.
calculated for pure hydrogen. Six months ago, this calculation
would have been of purely scientific interest, because pure
acetylene was a difiScult substance to procure ; but a very prac-
tical interest has been given it by the recent invention of Mr.
Thomas L. Willson of Brooklyn*, whereby pure acetylene can
be manufactured at a cost approximating 2 cents per pound.
Since the gas should theoretically reduce double its weight of
aluminium, if perfectly utilized for reduction, the cost of the re-
ducing agent per pound of aluminium would be very small. It
is to be hoped that the possibility of the above reaction may be
tested with this powerful reducing agent.
Before closing this subject of the thermal aspect of the reduc-
tion of aluminium compounds, it may be interesting to notice
some of the reactions which are of use in the aluminium indus-
try. It is well known that while chlorine gas can be passed
over ignited alumina without forming aluminium chloride, and
while carbon can be in contact with alumina at a white heat
without reducing it, yet the concurrent action of chlorine and
carbon will change the alumina into its chloride, a compound
with a lower heat of formation. Thus —
AL^Os -f- 3C = AI2 4- 3CO requires 304,500 cal.
But AI2O3 + 3C + 6C1 = 2AICI2 + 3CO requires a quantity of
heat equal to the 304,500 cal. minus 321,960, the heat of for-
mation of aluminium chloride, or in other words, 17,360 cal. is
evolved, showing that the reaction is one of easy practicability.
If it be inquired whether there is not some chloride which
would act on alumina to convert it into chloride, we would re-
mark that if we can find a chloride whose heat of formation is
as much greater than the heat of formation of the correspond-
ing oxide as the heat of formation of aluminium chloride is
greater than that of alumina, then such a chloride might react.
* See description in Engineering and Mining Journal, Dec. 15, 1894.
REDUCTION OF ALUMINIUM COMPOUNDS. 243
To be more particular, to convert alumina into aluminium
chloride, a deficit of 391,600 — 321,960 = 69,640 calories must
be made up. If we know of an element which in uniting with
3 atom weights (48 kilos) of oxygen gives out 69,640 calories
more heat, or a still greater excess, than in uniting with 6 atom
weights (213 kilos) of chlorine, then the chloride of that ele-
ment might perform the reaction. Now —
6Na + 3O = sNajO evolves 299,280 cal.
and 6Na + 6C1 =6NaCl evolves 586,140 cal.
leaving evidently a balance of 286,860 calories in the opposite
direction to what we are looking for. And so for every metal
except aluminium, I find the heat of formation of its chloride
greater than an equivalent quantity of its oxide. The only
element which I know to possess the opposite property is
hydrogen, for —
6H + 3O — 3H2O evolves 205,080 cal.
and 6H + 6C1 = 6HC1 evolves 132,000 cal.
and therefore the reaction —
AI2O3 + 6HC1 = 2AICI3 + 3H2C
would evolve according to our calculations (205, 080 — 132,000) —
69,640=3,440 calories, and would be thermally considered a pos-
sible reaction. Moreover, as a secondary effect, the water formed
is immediately seized by the aluminium chloride, for the reaction
2AICI3 + 3H2O = 2AICI3.3H2O evolves 153,690 cal.
and thus increases the total heat developed in the decom-
position of the alumina to 158, [30 calories. The result of
this reaction is therefore the hydrated chloride, which is of no
value for reduction by sodium, since when heated it decom-
poses into alumina and hydrochloric acid again, that is, it will
decompose before giving up its water, and the water if unde-
composed, or the acid if it decomposes, simply unites with the
244 ALUMINIUM.
sodium without affecting the alumina. The immense heat of
hydration, 153,690 calories, is so much greater than any other
known substance, that it is vain that we seek for any material
which might abstract the water and leave anhydrous aluminium
chloride.
Analagous to the reaction by which aluminium chloride is
formed from alumina is the reaction made use of for obtaining
aluminium sulphide, yet with some thermal considerations of a
different and highly interesting kind. If a mixture of alumina
and carbon is ignited and, instead of chlorine, sulphur vapor is
passed over it, no aluminium sulphide will be formed. An ex-
planation of this fact is seen on discussing the proposed reac-
tion thermally.
AI2O3 + 3C -I- 3S = AI2S3 + 3CO requires 180,200 cal.
It will be remembered that the similar reaction with chlorine
evolved 17,360 calories; the quantity causing this difference is
the heat of combination of aluminium sulphide, which is 321,960
— 124,400 = 197,560 calories less than that of aluminium
chloride, changing the excess of 17,360 calories into a deficit of
180,200 calories. This large negative quantity shows a priori
that the reaction could be made to occur only under excep-
tional conditions, and its non-occurrence under all conditions
so far tried gives evidence of the utility of the study of thermo-
chemistry, at least as a guide to experiment. However, while
carbon and sulphur cannot convert alumina into aluminium sul-
phide, carbon bisulphide can, for a current of the latter led over
ignited alumina converts it into aluminium sulphide. The re-
action taking place is
Al^Oa + 3CS2 = A1,S3 + 3COS.
Now, since carbon and sulphur by themselves could not per-
form the reaction, we should be very apt to reason that a com-
pound of carbon and sulphur would be still less able to do so,
since the heat absorbed in dissociating the carbon-sulphur
REDUCTION OF ALUMINIUM COMPOUNDS. 245
compound would cause a still greater deficit of heat. But here
-is precisely the explanation of the paradox. Carbon bisulphide
is one of those compounds, not frequent, which has a negative
heat of formation ( — 29,000 calories), i. e., heat is absorbed in
large quantity in its formation, and therefore, per contra, heat
is given out in the same quantity in its decomposition. The
heat of formation of carbon oxysulphide being 37,030 calories,
we can easily compute the thermal value of the reaction just
given.
Ifeat absorbed.
Decomposition of alumina 391,600 cal.
Heat developed.
Decomposition of carbon bisulphide 87,000
Formation of carbon oxysulphide 1 1 1,090
" of aluminium sulphide 124,400
322,490 cal.
Deficit of heat 69,1 10 "
It is thus seen that the reaction with carbon bisulphide is
less than one-half as strongly negative as the reaction with car-
bon and sulphur alone, and we therefore have an explanation
of the fact that the reaction with carbon bisulphide is easily
practicable, while the other is not. We do not know enough
about the variation of the heats of formation of aluminium sul-
phide and carbon oxysulphide to be able to make calculations
as accurately as was possible with the question of reducing alu-
mina, but if all the heats of formation remained constant except
that of alumina, the 69,000 calories deficit would be made up
by the decrease in the heat of formation of chat substance at
975O C, which is somewhere about the temperature at which
the reaction really takes place.
CHAPTER IX.
REDUCTION OF ALUMINIUM COMPOUNDS BY MEANS OF
POTASSIUM OR SODIUM.
The methods comprised under this heading may be con-
veniently divided into two classes : —
I. Methods based on the reduction of aluminium chloride
or aluminium-sodium chloride.
II. Methods based on the reduction of cryolite or aluminium
fluoride.
I.
The methods here included can be most logically presented
by taking them in chronological order.
Oerstedt's Experiments (1824).
After Davy's unsuccessful attempts to isolate aluminium by
the battery, in 1807, the next chemist to publish an account of
attempts in this direction was Oerstedt, who published a paper
in 1824 in a Swedish periodical.* Oerstedt's original paper is
thus translated into Berzelius's " Jahresbericht :"f
" Oerstedt mixes calcined and pure alumina, quite freshly
prepared, with powdered charcoal, puts it in a porcelain retort,
ignites and leads chlorine gas through. The coal then reduces
the alumina, and there results aluminium chloride and carbonic
oxide, and perhaps also some phosgene, COCI2 ; the alumin-
ium chloride is caught in the condenser and the gases escape.
The sublimate is white, crystalline, melts about the tempera-
ture of boiling water, easily attracts moisture, and evolves heat
* Oversigt over det K. Danske Videnskabemes Selkabs Forhandlingar og dets
Medlemmers Arbeider. May, 1824, to May, 1825, p. 15.
fBerz. Jahresb. der Chemie, 1827, vi. 1 1 8.
(246)
REDUCTION OF ALUMINIUM COMPOUNDS. 247
when in contact with water. If it is mixed with a concentrated
potassium amalgam and heated quickly, it is transformed ; there
results potassium chloride, and the aluminium unites with the
mercury. The new amalgam oxidizes in the air very quickly,
and gives as residue when distilled in a vacuum a lump of metal
resembling tin in color and lustre. In addition, Oerstedt found
many remarkable properties of the metal and of the amalgam,
but he holds them for a future communication after further in-
vestigation."
Oerstedt did not publish any other paper, and the next ad-
vance in the science is credited to Wohler, whom all agree in
naming as the true discoverer of the metal.
Wohler' s Experiments (1827).
In the following article from Poggendorff 's Annalen,* Wohler
reviews the article of Oerstedt's given above, and continues as
follows : —
" I have repeated this experiment of Oerstedt, but achieved
no very satisfactory result. By heating potassium amalgam
with aluminium chloride and distilling the product, there re-
mained behind a gray, melted mass of metal, but which, by
raising the heat to redness, went ofif as green vapor and distilled
as pure potassium. I have therefore looked around for another
method or way of conducting the operation, but, unpleasant as
it is to say it, the reduction of the aluminium fails each time.
Since, however, Herr Oerstedt remarks at the end of his paper
that he did not regard his investigations in aluminium as yet
ended, and already several years have passed since then, it
looks as if I had taken up one of those researches begun aus-
piciously by another (but not finished by him), because it
promised new and splendid results. I must remark, however,
that Herr Oerstedt has indirectly by his silence encouraged me
to try to attain to further results myself. Before I give the art
how one can quite easily reduce the metal, I will say a few
words about aluminium chloride and its production (see p. 152).
* Pogg. Ann., 1827, ii. 147.
248 ALUMINIUM.
" I based the method of reducing aluminium on the reaction
of aluminium chloride on potassium, and on the property of the
metal not to oxidize in water. I warmed in a glass retort a
small piece of the aluminium salt with some potassium, and the
retort was shattered with a strong explosion. I tried then to do
it in a small platinum crucible, in which it succeeded very well.
The reaction is always so violent that the cover must be weighted
down, or it will be blown off; and at the moment of reduction,
although the crucible be only feebly heated from outside, it
suddenly glows inside, and the platinum is almost torn by the
sudden shocks. In order to avoid any mixture of platinum
with the reduced aluminium, I next made the reduction in a
porcelain crucible, and succeeded then in the following manner :
Put in the bottom of the crucible a piece of potassium free from
carbon and oil, and cover this with an equal volume of pieces
of aluminium chloride. Cover and heat over a spirit lamp, at
first gently, that the crucible be not broken by the production of
heat inside, and then heat stronger, at last to redness. Cool,
and when fully cold put it into a glass of cold water. A gray
powder separates out, which on nearer observation, especially
in sunlight, is seen to consist of little flakes of metal. After it
has separated, pour off the solution, filter, wash with cold
water, and dry; this is the aluminium."
In reality, this powder possessed no metallic properties, and
moreover, it contained potassium and aluminium chloride,
which gave it the property of decomposing water at 100°. To
avoid the loss of aluminium chloride by volatilization at the
high heat developed during the reaction, Liebig afterwards
made its vapors pass slowly over some potassium placed in a
long glass tube. This device of Liebig is nearly the arrange-
ment which Wohler adopted later, in 1845, ^nd which gave him
much better results.
Wbklcr's Experiments ( 1 845 ) .
The following is Wohler's second paper published in 1845 ■*
* Liebig's Annalen, 53, 422.
REDUCTION OF ALUMINIUM COMPOUNDS. 249
" On account of the violent incandescence with which the
reduction of aluminium chloride by potassium is accompanied,
this operation requires great precautions, and can be carried
out only on a small scale. I took for the operation a platinum
tube, in which I placed aluminium chloride, and near it some
potassium in a platinum boat. I heated the tube gently at first,
then to redness. But the reduction may also be done by put-
ting potassium in a small crucible, which is placed inside a
larger one, and the space between the two filled with aluminium
chloride. A close cover is put over the whole, and it is heated.
Equal volumes ot potassium and the aluminium salt are the
best proportions to employ. After cooling, the tube or cruci-
ble is put in a vessel of water. The metal is obtained as a gray
metallic powder, but on closer observation one can see even
with the naked eye small tin-white globules, some as large as
pins' heads. Under the microscope magnifying two hundred
diameters, the whole powder resolves itself into small globules,
several of which may sometimes be seen sticking together,
showing that the metal was melted at the moment of reduction.
A beaten-out globule may be again melted to a sphere in a
bead of borax or salt of phosphorus, but rapidly oxidizes dur-
ing the operation, and if the heat is continued, disappears
entirely, seeming either to reduce boric acid in the borax bead,
or phosphoric acid in the salt of phosphorus bead. I did not
succeed in melting together the pulverulent aluminium in a
crucibe with borax, at a temperature which would have melted
cast-iron, for the metal disappeared entirely and the borax be-
came a black slag. It seems probable that aluminium, being
lighter than molten borax, swims on it and burns. The white
metallic globules had the color and lustre of tin. It is perfectly
malleable and can be hammered out to the thinnest leaves.
Its specific gravity, determined with two globules weighing 32
milligrammes, was 2.50, and with three hammered- out globules
weighing 34 milligrammes, 2.67. On account of their lightness
these figures can only be approximate. It is not magnetic,
remains white in the air, decomposes water at 100°, not at
250 ALUMINIUM.
usual temperatures, and dissolves completely in caustic potash
(KOH). When heated in oxygen almost to melting, it is only
superficially oxidized, but it burns like zinc in a blast-lamp
flame."
These results of Wohler's, especially the determination of
specific gravity, were singularly accurate when we consider
that he established them working with microscopic bits of
the metal, It was just such work that established Wohler's
fame as an investigator. However, we notice that his metal
differed from aluminium as we know it in several important
respects, in speaking of which Deville says: "All this time
the metal obtained by Wohler was far from being pure ; it was
very difficultly fusible, owing, without doubt, to the fact that
it contained platinum taken from the vessel in which it had
been prepared. It. is well known that these two metals com-
bine very easily at a gentle heat. Moreover, it decomposed
water at 100°, which must be attributed either to the presence
of potassium or to aluminium chloride, with which the metal
might have been impregnated : for aluminium in presence of
aluminium chloride in effect decomposes water with evolution
of hydrogen."
After Wohler's paper in 1845, the next improvement is that
introduced by Deville in 1854-55, and this is really the date at
which aluminium, the metal, became known and its true proper-
ties established.
Deville s Experiments (1854).
The results of this chemist's investigations and success in
obtaining pure aluminium were first made public at the seance
of the French Academy, August 14, 1854, and included men-
tion of an electrolytic method of reduction (see Chap. XI.), as
well as of the following on reduction by sodium.*
" The following is the best method for obtaining aluminium
chemically pure in the laboratory. Take a large glass tube
about four centimeters in diameter, and put into it 200 or 300
* Ann. de Phys. et de Chim., xliii. 24.
REDUCTION OF ALUMINIUM COMPOUNDS. 2$ I
grammes of pure aluminium chloride free from iron, and isolate
it between two stoppers of amianthus (fine, silky asbestos).
Hydrogen, well dried and free from air, is brought in at one
end of the tube. The aluminium chloride is heated in this cur-
rent of gas by some lumps of charcoal in order to drive ofif
hydrochloric acid or sulphides of chlorine or of silicon, with
which it is always impregnated. Then there are introduced into
the tube porcelain boats, as large as possible, each containing
several grammes of sodium, which was previously rubbed quite
dry between leaves of filter paper. The tube being full of
hydrogen, the sodium is melted, the aluminium chloride is
heated and distils, and decomposes in contact with the sodium
with incandesence, the intensity of which can be moderated at
pleasure. The operation is ended when all the sodium has dis-
appeared, and when the sodium chloride formed has absorbed
so much aluminium chloride as to be saturated with it. The
aluminium which has been formed is held in the double chloride
of sodium and aluminium, AlClg.NaCl, a compound very fusible
and very volatile. The boats are then taken from the glass
tube, and their entire contents put in boats made of retort car-
bon, which have been previously heated in dry chlorine in order
to remove all siliceous and ferruginous matter. These are then
introduced into a large porcelain tube, furnished with a pro-
longation and traversed by a current of hydrogen, dry and free
from air. This tube being then heated to bright redness, the
aluminium-sodium chloride distils without decomposition and
condenses in the prolongation. There is found in the boats,
after the operation, all the aluminium which had been reduced,
collected in at most one or two small buttons. The boats when
taken from the tube should be nearly free from aluminium-
sodium chloride, and also from sodium chloride. The buttons
of aluminium are united in a small earthenware crucible, which
is heated as gently as possible, just sufificient to melt the metal.
The latter is pressed together and skimmed clean by a small
rod or tube of clay. The metal thus collected may be very
suitably cast in an ingot mould."
252 ALUMINIUM.
The later precautions added to the above given process were
principally directed towards avoiding the attacking of the cruci-
ble, which always takes place when the metal is melted with a
flux, and the aluminium thereby made more or less siliceous.
The year following the publication of these results, this labora-
tory method was carried out on a large scale at the chemical
works at Javel.
Deville's Methods (1855).
The methods about to be given are those which were devised
in Deville's laboratory at the Ecole Normale, during the winter
of 1854-55, and applied on a large scale at Javel, during the
spring of 1855 (March-July). The Emperor Napoleon III.
defrayed the expenses of this installation. Descriptions of the
methods used for producing alumina, aluminium chloride and
sodium at Javel can be found under their respective headings
(pp. 134, 153, 180), We here confine our description to
the mode of reducing the aluminium chloride by sodium, and
the remarks incident thereto. The process has at present
only an historic interest, as it was soon modified in its details
so as to be almost entirely changed. The following is Deville's
description : —
" Perfectly pure aluminium. — To obtain aluminium perfectly
pure it is necessary to employ materials of absolute purity, to
reduce the metal in presence of a completely volatile flux, and
finally never to heat, especially with a flux, in a siliceous vessel
to a high temperature.
" Pure materials. — The necessity of using absolutely pure
materials is easy to understand ; all the metallic impurities are
concentrated in the aluminium, and unfortunately I know no
absolute method of purifying the metal. Thus, suppose we
take an alum containing o.i per cent, of iron and 11 per cent,
of alumina; the alumina derived from it will contain i per
cent, of iron, and supposing the alumina to give up all the alu-
minium in it, the metal will be contaminated with 2 per cent,
of iron.
REDUCTION OF ALUMINIUM COMPOUNDS.
253
'^Influence of flux or slag. — The flux, or the product of the
reaction of the sodium on the aluminous material, ought to be
volatile, that one may separate the aluminium by heat from the
material with which it has been in contact, and with which it
remains obstinately impregnated because of its small specific
gravity.
" Influence of the vessel. — The siliceous vessels in which
aluminium is received or melted give it necessarily a large
quantity of silicon, a very injurious impurity. Silicon cannot
be separated from aluminium by any means, and the siliceous
aluminium seems to have a greater tendency to take up more
silicon than pure aluminium, so that after a small number of
remeltings in siliceous vessels the metal becomes so impure as
to be almost infusible.
In order to avoid the dangers pointed out above, Deville re-
commended following scrupulously the following details in
order to get pure aluminium.
" Reduction of solid sodium. — The crude aluminium chloride
placed in the cyHnder A (Fig. 23), is vaporized by the fire and
,-JL,
Fig. 24.
r
1
I to.»»iaa Y^s;^ teMaa "T
passes through the tube to the cylinder B, containing 60 to 80
kilos of iron nails heated to a dull-red heat. The iron retains
as relatively fixed ferrous chloride, the ferric chloride and
hydrochloric acid which contaminate the aluminium chloride,
and likewise transforms any sulphur dichloride (SCl^) in it into
ferrous chloride and sulphide of iron. The vapors on passing
out of B through the tube, which is kept at about 300°, deposit
254 ALUMINIUM.
spangles of ferrous chloride, which is without sensible tension
at that temperature. The vapors then enter D, a cast-iron
cylinder in which are three cast-iron boats each containing 500
grms. of sodium. It is sufficient to heat this cylinder barely to
a dull-red heat in its lower part, for the reaction once com-
menced disengages enough heat to complete itself, and it is
often necessary to take awav all the fire from it. There is at
first produced in the first boat some aluminium and some sod-
ium chloride, which latter combines with the excess of alumin-
ium chloride to form the volatile aluminium-sodium chloride,
AlClj.NaCl. These vapors of double chloride condense on the
second boat and are decomposed by the sodium into alumin-
ium and sodium chloride. A similar reaction takes place in
the third boat when all the sodium of the second has disap-
peared. When on raising the cover it is seen that the
sodium of the last boat is entirely transformed into a lumpy
black material, and that the reactions are over, the boats
are taken out, immediately replaced by others, and are al-
lowed to cool covered by empty boats. In this first opera-
tion the reaction is rarely complete, for the sodium is
protected by the layer of sodium chloride formed at its ex-
pense. To make this disappear, the contents of the boats are
put into cast-iron pots or earthen crucibles, which are heated
until the aluminium chloride begins to volatilize, when the so-
dium will be entirely absorbed and the aluminium finally re-
mains in contact with a large excess of its chloride, which is
indispensable for the success of the operation. Then the pots
or crucibles are cooled, and there is taken from the upper part
of their contents a layer of sodium chloride almost pure, while
underneath are found globules of aluminium which are sepa-
rated from the residue by washing with water. Unfortunately
the water in dissolving the aluminium chloride of the flux exer-
cises on the metal a very rapid destructive action, and only
the globules larger than the head of a pin are saved from this
washing. These are gathered together, dried, melted in an
earthen crucible, and pressed together with a clay rod.
REDUCTION OF ALUMINIUM COMPOUNDS. 255
The button is then cast in an ingot mould. It is important in
this operation to employ only well-purified sodium, and not to
melt the aluminium if it still contains any sodium, for in this
case the metal takes fire and burns as long as any of the alka-
line metal remains in it. In such a case it is necessary to re-
melt in presence of a little aluminium-sodium chloride.
" Such is the detestable process by means of which were made
the ingots of aluminium sent to the Exhibition (1855). To
complete my dissatisfaction at the processs, pressed by time and
ignorant of the action of copper on aluminium, I employed in
almost all my experiments reaction cylinders and boats of cop-
per, so that the aluminium I took from them contained such
quantities of this metal as to form a veritable alloy. Moreover, it
had lost almost all ductility and malleability, had a disagreeable
gray tint, and finally at the end of two months it tarnished by
becoming covered with a black layer of oxide or sulphide of
copper, which could only be removed by dipping in nitric acid.
But, singular to relate, an ingot of virgin silver which had been
put alongside the aluminium that the public might note easily
the difference in color and weight of the two metals, was
blackened still worse than the impure aluminium. Only one of
the bars exhibited, which contained no copper, remained un-
altered from the day of its manufacture till now (1859). It
was some of this cupreous aluminium that I sent to M.
Regnault, who had asked me for some in order to determine its
specific heat. I had cautioned him at the time of the number
and nature of the impurities which it might contain, and the
analysis of M. Salvetat, which is cited in the memoir of
Regnault, accords with the mean composition of the specimens
that I had produced and analyzed at that time (see p. 54,
Analysis i). It is to be regretted that I gave such impure
material to serve for determinations of such splendid precision.
I was persuaded to do so only by the entreaties of M.
Regnault, who could not wait until I prepared him better. It is
also this cupreous aluminium which M. Hulot has called ' hard
aluminium,' in a note on the physical properties of this metal
256 ALUMINIUM.
which he addressed to the Academy. Hulot has remarked
that this impure metal, which is crystalline in structure, after
having been compressed between the dies of the coining press
may lose its crystalline structure, to which it owes its brittle-
ness, and become very malleable. It possesses then such
strength that it works well in the rolls of a steel rolling mill.
Further, this 'hard aluminium' becomes quite unalterable when
it has thus lost its texture.
"Reduction by sodium vapor. — This process, which I have not
perfected, is very easy to operate, and gave me very pure metal
at the first attempt. I operate as follows : I fill a mercury bot-
tle with a mixture of chalk, carbon, and carbonate of soda, in
the proportions best for generating sodium. An iron tube
about ten centimetres long is screwed to the bottle, and the
whole placed in a wind furnace, so that the bottle is heated to
red-white and the tube is red to its end. The end of the tube
is then introduced into a hole made in a large earthen crucible
about one-fourth way from the bottom, so that the end of the
tube just reaches the inside surface of the crucible. The car-
bonic oxide (CO) disengaged burns in the bottom of the cru-
cible, heating and drying it ; afterwards the sodium flame
appears, and then pieces of aluminium chloride are thrown into
the crucible from time to time. The salt volatilizes and de-
composes before this sort of tuyere, from which issues the
reducing vapor. More aluminium salt is added when the
vapors coming from the crucible cease to be acid, and when
the flame of sodium burning in the atmosphere of aluminium
chloride loses its brightness. When the operation is finished,
the crucible is broken and there is taken from the walls below
the entrance of the tube a saline mass composed of sodium
chloride, a considerable quantity of globules of aluminium, and
some sodium carbonate, which latter is in larger quantity the
slower the operation was performed. The globules are de-
tached by plunging the saline mass into water, when it be-
comes necessary to notice the reaction of the water on litmus.
If the water becomes acid, it is renewed often ; if alkaline, the
REDUCTION OF ALUMINIUM COMPOUNDS. 257
mass, impregnated with metal, must be digested in nitric acid,
diluted with three or four volumes of water, and so the metal is
left intact. The globules are reunited by melting with the
precautions before given."
Deville's Process (1859).
The process then in use at Nanterre was based on the use of
aluminium-sodium chloride, which was reduced by sodium,
with cryolite or fluorspar as a flux. The methods of preparing
each of these materials were carefully studied out at the chem-
ical works of La Glaciere, where, from April, 1856, to April,
1857, the manufacture of aluminium was carried on by a com-
pany formed by Deville and a few friends, and from thence
proceeded the actual system which was established at Nanterre
under the direction of M. Paul Morin when the works at La
Glaciere were closed. The methods of preparation of alumina,
aluminium-sodium chloride and sodium used at Nanterre are
placed under their respective, headings (pp. 137, 154, 190).
In the first year that the works at Nanterre were in opera-
tion there were made :
Aluminium-sodium chloride 10,000 kilos.
Sodium 2,000 "
Aluminium 600 "
The metal prepared improved constantly in quality, M. Morin
profiting continually by his experience and improving the
practical details constantly, so that the aluminium averaged, in
1859, gj per cent. pure. (See Analysis 9, p. 54.)
As to the rationale of the process used, aluminium chloride
was replaced by aluminium-sodium chloride because the latter
is less deliquescent and less difficult of preservation ; but the.
small amount of moisture absorbed by the double chloride is
held very energetically, at a high temperature giving rise to
some alumina, which encloses the globules of metal with a thin
coating, and so hinders their easy reunion to a button. Deville
remarked that the presence of fluorides facilitated the reunion
17
258 ALUMINIUM.
of these globules, which fact he attributed to their dissolving
the thin coat of alumina ; so that the employment of a fluoride
as a flux became necessary to overcome the effect produced
primarily by the aluminium-sodium chloride holding moisture
so energetically. Deville gives the following account of the
development of these improvements : "The facility with which
aluminium unites in fluorides is due without doubt to the prop-
erty which these possess of dissolving the alumina on the sur-
face of the globules at the moment of their formation, and
which the sodium is unable to reduce. I had experienced great
difificulty by obtaining small quantities of metal poorly united,
when I reduced the aluminium-sodium chloride by sodium ;
M. Rammelsberg, who often made the same attempts, tells me
he has had a Hke experience. But I am assured by a scrupu-
lous analysis that the quantity of metal reduced by the sodium
is exactly that which theory indicates, although after many
operations there is found only a gray powder, resolving itself
under the microscope into a multitude of small globules. The
fact is simply that aluminium-sodium chloride is a very poor
flux for aluminium. MM. Morin, Debray, and myself have
undertaken to correct this bad effect by the introduction of a
solvent for the alumina into the saline slag which accompanies
the aluminium at the moment of its formation. At first, we
found it an improvement to condense the vapors of aluminium
chloride, previously purified by iron, directly in sodium chloride,
placed for this purpose in a crucible and kept at a red heat.
We produced in this way, from highly colored material, a double
chloride very white and free from moisture, and furnishing on
reduction a metal of fine appearance. We then introduced
fluorspar (CaF^) into the composition of the mixture to be
reduced, and we obtained good results with the following pro-
portions :
Aluminium-sodium chloride 400 grammes.
Sodium chloride 200 "
Calcium fluoride 200 "
Sodium 75 to 80 "
REDUCTION OF ALUMINIUM COMPOUNDS. 259
" The double chloride ought to be melted and heated almost
to low red heat at the moment it is employed, the sodium
chloride calcined and at a red heat or melted, and the fluorspar
pulverized and well dried. The double chldride, sodium chlor-
ide and calcium fluoride are mixed and alternated in layers in
the crucible with sodium. The top layer is of the mixture, and
the cover is sodium chloride. Heat gently, at first, until the
reaction ends, and then to a heat about sufficient to melt silver.
The crucible, or at least that part of it which contains the mix-
ture, ought to be of a uniform red tint, and the material per-
fectly liquid. It is stirred a long time and cast on a well dried,
chalked plate. There flows out first a very limpid liquid, col-
orless and very fluid ; then a gray material, a little more pasty,
which contains aluminium in little grains, and is set aside ; and
finally a button with small, metallic masses which of them-
selves ought to weigh 20 grms. if the operation has succeeded
well. On pulverizing and sieving the gray slag, 5 or 6 grms.
of small globules are obtained, which may be pressed together
by an earthen rod in an ordinary crucible heated to redness.
The globules are thus reunited, and when a sufficient quantity
is collected the metal is cast into ingots. In a well-conducted
operation, 75 grms. of sodium ought to give a button of 20
grms. and S grms. in grains, making a return of one part alu-
minium from three of sodium. Theory indicates one to two
and a half, or 30 grms. of aluminium from 75 of sodium. But
all the efforts which have been made to recover from the inso-
luble slag the 4 or 5 grms. of metal not united, but easily vis-
ible with a glass, have been so far unsuccessful. There is,
without doubt, a knack, a particular manipulation, on which de-
pends the success of an operation which would render the
theoretical amount of metal, but we lack it yet. These opera-
tions take place, in general, with more facility on a large scale,
so that we may consider fluorspar as being suitable for serving
in the manufacture of aluminium in crucibles. We employed
very pure fluorspar, and our metal was quite exempt from
silicon. It is true that we took a precaution which is necessary
260 ALUMINIUM.
to adopt in operations of this kind ; we plastered our crucibles
inside with a layer of aluminous paste, the composition of
which has been given in 'Ann. de Chim. et de Phys.' xlvi. 195.
This paste is made of calcined alumina and an aluminate of
lime, the latter obtained by heating together equal parts of
chalk and alumina to a high heat. By taking about four parts
calcined alumina and one of aluminate of lime well pulverized
and sieved, moistening with a little water, there is obtained a
paste with which the inside of an earthen crucible is quickly
and easily coated. The paste is spread evenly with a porcelain
spatula, and compressed strongly until its surface has become
well polished. It is allowed to dry, and then heated to bright
redness to season the coating, which does not melt, and pro-
tects the crucible completely against the action of the alumin-
ium and fluorspar. A crucible will serve several times in suc-
cession, provided that the new material is put in as soon as the
previous charge is cast. The advantages of doing this are
that the mixture and the sodium are put into a crucible al-
ready heated up, and so lose less by volatilization because the
heating is done more quickly, and the crucible is drier than if
a new one had been used or than if it had been let cool. A
new crucible should be heated to at least 300° or 400° before
being used. The saline slag contains a large quantity of cal-
cium chloride, which can be washed away by water, and an in-
soluble material from which aluminium fluoride can be volatil-
ized.
" Yet the operation just described, which was a great im-
provement on previous ones, requires many precautions and a
certain skill of manipulation to succeed every time. But
nothing is more easy or simple than to substitute cryolite for
the fluorspar. Then the operation is much easier. The
amount of metal produced is not much larger, although the
button often weighs 22 grammes, yet if cryolite can only be ob-
tained in abundance in a continuous supply, the process which
I will describe will become most economical. The charge is
made up as before, except introducing cryolite for fluorspar.
REDUCTION OF ALUMINIUM COMPOUNDS. 26 1
In one of our operations we obtained, with -j^ grms. of sodium,
a button weighing 22 grms. and 4 grms. in globules, giving a
yield of one part aluminium to two and eight-tenths parts
sodium, which is very near to that indicated by theory. The
metal obtained was of excellent quality. However, it con-
tained a little iron coming from the aluminium chloride, which
had not been purified perfectly. But iron does not injure the
properties of the metal as copper does ; and, save a little bluish
coloration, it does not alter its appearance or its resistance to
physical and chemical agencies.
" After these attempts we tried performing the reduction sim-
ply on the bed of a reverberatory furnace, relying on the imme-
diate reaction of sodium on the double chloride to use up these
materials before they could be perceptibly wasted by the fur-
nace gases. This condition was realized in practice with
unlooked-for success. The reduction is now made on a some-
what considerable scale at the Nanterre works, and never, since
commencing to operate in this way, has a reduction failed, the
results obtained being always uniform. The furnace now used
has all the relative dimensions of a soda furnace. In fact,
almost the temperature of an ordinary soda furnace is required
that the operation may succeed perfectly. The absolute dimen-
sions of the furnace, however, may vary with the quantity of alu-
minium to be made in one operation, and are not limited. With
a bed of one square metre surface, 6 to 10 kilos of aluminium
can be reduced at once ; and since each operation lasts about
four hours, and the furnace may be recharged immediately after
emptying it of the materials just treated, it is seen that, with so
small a bed, 60 to lOO kilos of aluminium can be made in
twenty-four hours without any difficulty. In this respect, I
think the industrial problem perfectly solved. The proportions
which we employed at first were —
Aluminium-sodium chloride (crushed) 10 parts.
Fluorspar 5 "
Sodium (in ingots) 2 "
" As aluminium is still very dear, it is necessary to direct
262 ALUMINIUM.
great attention to the return from the materials used, and on
this point there is yet much progress to be made. We ascer-
tained many times that the return was always a little better, and
the reunion of the metal to a single ingot a little easier, when
cryolite was substituted for fluorspar, the price of the former,
after having been high, being now lowered to 350 francs per
tonne (about $75 per long ton). For this reason we can now
use cryolite instead of fluorspar, and in the same proportions.
We can also recover alumina from this cryolite by treating the
slags (see p. 148). The double chloride and pulverized cryo-
lite are now mixed with the sodium in small ingots, and the
mixture thrown on to the bed of the heated-up furnace. The
dampers are then shut, to prevent as much as possible access
of air. Very soon a lively reaction begins, with the production
of such heat that the brick sides of the furnace, as well as the
materials on the hearth, are made bright red-hot. At this heat
the mixture is almost completely fused. Then it is necessary
to open the damper and direct the flame on the bed in such
manner as to heat the bath equally all over and unite the re-
duced aluminium. When the operation is considered ended, a
casting is made by an opening in the back of the furnace and
the slag is received in cast-iron pots. At the end of the cast
the aluminium arrives in a single jet, which unites into a single
lump at the bottom of the still-liquid slag. The gray slag flow-
ing out last should be pulverized and sieved, to extract the
divided globules of aluminium, 200 to 300 grammes of which
can sometimes be extracted from one kilo of gray slag. The
pulverization of the slag is in all cases indispensable in its sub-
sequent treatment for extracting its alumina. The slag is of
two kinds, one fluid and light, which covered the bath, and is
rich in sodium chloride ; the other less fusible and pasty, gray
in color, which is more dense and lies in contact with the alu-
minium. The coloring material producing the grayness is car-
bon, coming either from the sodium or from the oil which im-
pregnated it, or finally from the vapor of the oil. I attribute
the slight pastiness of this slag to a little alumina dissolved by
the fluorides. This slag contains about:
REDUCTION OF ALUMINIUM COMPOUNDS. 263
Sodium chloride 60 parts.
Aluminium fluoride 40 "
and on washing it the former dissolves while the latter remains,
mixed with a little cryolite or alumina. This is the alumina
which had been dissolved or retained in the bath of fluoride.
It will be remarked that the bath of slag contains no other
fluoride than aluminium fluoride, which does not attack earthen
crucibles or siliceous materials in general except at a very high
temperature. It is for this reason that the hearth and other parts
of the furnace resist easily a fluoride slag containing only alu-
minium fluoride, which has not the property of combining with
silicon fluoride at the expense of the silica of the bricks — as
sodium fluoride does in like circumstances. In our operations,
cryolite is used only as a flux. In the process of reduction
based on cryolite alone, the sodium fluoride resulting is, on the
contrary, very dangerous to crucibles, and it is due to that fact
especially that the aluminium absorbs a large quantity of
silicon, which always happens with this method. In fact, it is
well known that metallic silicon can be prepared in this way by
prolonging the operation a little."
Deville closes his account of the aluminium industry in 1859
with these words : " Many things yet remain to us to do, and
we can scarcely say now that we know the true qualities of the
substances we employ. But the matter is so new, is harassed
with so many difiSculties even after all that has been done, that
our young enterprise may hope everything from the future when
it shall have acquired experience. I ought to say, however,
that the aluminium industry is now at such a point that if the
uses of the metal are rapidly extended it may change its aspect
with great rapidity. One may ask to-day how much a kilo of
iron would cost if a works made only 60 to 100 kilos of it a
month, if large apparatus were excluded from this industry, and
iron obtained by laboratory processes which would permit it to
become useful only by tedious after-treatment. Such will not
be the case with aluminium, at least with the processes just de-
scribed. In fact in all I undertook, either alone or with my
264 ALUMINIUM.
friends, I have always been guided by this thought — that we
ought to adopt only such apparatus as is susceptible of being
immediately enlarged, and to use only materials almost as com-
mon as clay itself for the source of the aluminium."
The Deville Process (1882).
The process just described reached a fair degree of perfec-
tion at Nanterre, under the direction of M. Paul Morin. After-
wards, some of the chemical operations incidental to the
process were carried on at the works of the Chemical Manufac-
turing Company of Alais and Carmargue, at Salindres (Gard),
owned by H. Merle & Co. At a later date the whole manufac-
ture was removed to this place, while the Societe Anonyme de
1' Aluminium, at Nanterre, worked up the metal, and placed it
on the market. The Salindres works, about 1880, went under
the management of A. R. Pechiney & Co., and under the per-
sonal attention of M. Pechiney, the Deville process reached its
perfection. The following account is taken mostly from M.
Margottet's article on aluminium in Fremy's Encyclopedic
Chimique.
An outline of the process, as it was prepared, may very
appropriately be given at this place, although detailed descrip-
tions of the preliminary processes for preparing the materials
for reduction are given under the appropriate headings (see
pp. 137, 154, 190).
The primary material to furnish the aluminium is bauxite.
To obtain the metal it is necessary to proceed successively
through the following operations: —
I. Preparation of the aluminate of soda, and solution of this
salt to separate it from the ferric oxide contained in the
bauxite.
II. Precipitation of hydrated alumina from the aluminate of
soda by a current of carbon dioxide ; washing the precipitate.
III. Preparation of a mixture of alumina, carbon, and salt,
drying it, and then treating with gaseous chlorine to obtain the
double chloride of aluminium and sodium.
REDUCTION OF ALUMINIUM COMPOUNDS. 265
IV. Lastly, treatment of this chloride by sodium to obtain
aluminium.
The principal chemical reactions on which this process rests
are the following: —
Formation of aluminate of soda by calcining bauxite with
sodium carbonate —
(AlFe) A.2H,0 + 3Na,C03=-Al,03-3Na,0 + Fe.Oa
+ 2H,0 + 3CO,.
Formation of alumina by precipitating the aluminate of soda
with a current of carbon dioxide —
Al,03-3Na,0 + 3CO, + 3H,0 = Al.Os.sH.O + 3Na,C03.
Formation of aluminium-sodium chloride by the action of
chlorine on a mixture of alumina, carbon, and sodium chloride —
AI2O3 + 3C + 2NaCl + 6C1 = 2 (AlCla.NaCl) + 3CO.
Reduction of this double chloride by sodium —
AlCIs.NaCl + 3Na = Al + 4NaCl.
As observed before, we will here consider only the last oper-
ation. The advances made since 1859 are mostly in matters of
detail, which every one knows are generally the most import-
ant part of a process ; and so, although a few of the details
may be repeated, yet we think it best not to break the contin-
uity of this description by excising those few sentences which
are nearly identical in the two accounts.
The difiSculty of this operation, at least from an industrial
point of view, is to get a slag fusible enough and light enough
to let the reduced metal easily sink through it and unite.
This result has been reached by using cryolite. This material
iorms with the sodium chloride resulting from the reaction a
very fusible slag, in the midst of which the aluminium collects
well, and falls to the bottom. In one operation the charge is
now composed of —
266 ALUMINIUM.
100 kilos Aluminium-sodium chloride.
45 " Cryolite.
35 " Sodium.
The double chloride and cryolite are pulverized, the sodium^
cut into small pieces a little larger than the thumb, is divided
into three equal parts, each part being put into a sheet-iron
basket. The mixture of double chloride and cryolite, being
pulverized, is divided into four equal parts, three of these are
respectively put in each basket with the sodium, the fourth
being placed in a basket by itself. The reduction furnace (see
Fig. 25.
r
a.
Fig. 25) is a little furnace of refractory brick, with an inclined
hearth and a vaulted roof. This furnace is strongly braced by
iron tie-rods, because of the concussions caused by the reac-
tion. The flame may at any given moment be directed into a.
flue outside of the hearth. At the back part of the furnace,,
that is to say, on that side towards which the bed slopes, is a
little brick wah which is built up for each reduction and is.
taken away in operating the running out of the metal and slag>
A gutter of cast-iron is placed immediately in front of the wall
to facilitate running out the materials. All this side of the fur-
nace ought to be opened or closed at pleasure by means of a
damper. Lastly, there is an opening for charging in the roof,
closed by a lid. At the time of an operation the furnace
should be heated to low redness, then are introduced in rapid
REDUCTION OF ALUMINIUM COMPOUNDS. 267
succession the contents of the three baskets containing sodium,
etc., and lastly the fourth containing only double chloride and
no sodium. Then all the openings of the furnace are closed,
and a very vivid reaction accompanied by dull concussions im-
mediately takes place. At the end of fifteen minutes, the ac-
tion subsides, the dampers are opened and the heat continued,
meanwhile stirring the mass from time to time with an iron
poker. At the end of three hours the reduction is ended, and
the metal collects at the bottom of the liquid bath. Then the
running out is proceeded with in three phases : First — Running
off the upper part of the bath, which consists of a fluid material
completely free from reduced aluminium and constituting the
white slag. To run this out a brick is taken away from the
upper course of the little wall which terminates the hearth.
These slags are received in an iron wagon. Second — Running
out the aluminium. This is done by opening a small orifice
left in the bottom of the brick wall, which was temporarily
plugged up. The liquid metal is received in a cast-iron melt-
ing pot, the bottom of which has been previously heated to
redness. The aluminium is immediately cast in a series of
small rectangular cast-iron moulds. Third — Running out of
the rest of the bath, which constitutes the gray slags. These
were, like the white slags, formed by the sodium chloride and
cryolite, but they contain, in addition, isolated globules of alu-
minium. To run these out, all the bricks of the little wall are
taken away.. , This slag is received in the same melting pot into
which the aluminium was run, the latter having been already
moulded. Here it cools gradually, and after cooling there are
always found at the bottom of the pot several grains of metal.
In a good operation there are taken from one casting 10.5
kilos of aluminium, which is sold directly as commercial metal.
The following data as to the expense of this process may be
very appropriately inserted here, giving the cost at Salindres in
1873, in which year 3600 kilos are said to have been made.
* Manufacture of one kilo of aluminium.
* A. Wurtz, Wagner's Jahresb., 1874, vol. xxi.
268 ALUMINIUM.
Sodium 3.44 kilos @ 11.32 fr. per kilo = 38 fr. 90 cent.
Aluminium-sodium
chloride. . . . 10.04 " 2.48 " " = 24 " 90 "
Cryolite 3.87 " 61.0 " 100 kilos ^ 2 " 36 "
Coal 29.17 " 1.40 " " = o " 41 "
Wages I " 80 "
Costs o " 88 "
Total 69 " 25 "
This must be increased ten per cent, for losses and other ex-
penses, making the cost of aluminium 80 fr. per kilo, and it is
sold for 100. ($9.00 per lb.)
According to a statement in the ' Bull, de la Soc. de I'lndustrie
Minerale,' ii. 451, made in 1882, Salindres was then the only
place in which aluminium was being manufactured. The
Deville process was finally driven out of the market, and the
manufacture at Salindres suspended, in 1890.
Niewerth's Process (1883).
This method can be regarded as little more than a suggestion,
since it follows exactly the lines of some of Deville's earlier ex-
periments. Although theoretically very advantageous, yet in
practice it has probably been found far inferior in point of yield
of metal and expense to the ordinary sodium processes. The
patent is taken out in the United States and other countries in
the name of H. Niewerth, of Hanover, and is thus summarized :
*A compound of aluminium, with chlorine or fluorine, is
brought by any means into the form of vapor, and conducted,
strongly heated, into contact with a mixture of 62 parts sodium
carbonate, 28 coal, and 10 chalk, which is also in a highly heated
condition. This mixture disengages sodium, which reduces the
gaseous chloride or fluoride of aluminium, the nascent sodium
being the reducing agent. In place of the above mixture other
suitable mixtures which generate sodium may be employed, or
mixtures may also advantageously be used from which potassium
is generated.
* Sci. Am. Supple., Nov. 17, 1883.
REDUCTION OF ALUMINIUM COMPOUNDS. 269
Gadsden's Patent (1883).
H. A. Gadsden, of London, and E. Foote,* of New York,
were granted a patent based on the principle of heating in a
retort sodium carbonate and carbonaceous matter, or any suit-
able mixture for generating sodium, and conducting the vapor
of sodium produced into another retort, lined with carbon, in
which aluminium chloride, or aluminium-sodium chloride or
cryolite, has been placed and heated. The second English pat-
ent claims to heat a mixture which will generate sodium in one
retort, and pass chlorine over a mixture of carbon and alum-
ina, thus generating aluminium chloride, in another retort, and
then mixing the two vapors in a third retort or reaction
chamber.
Friskmuth's Process (1884).
This was patented in the United States in 1884 (U. S. Pat.
308,152, Nov. 1884). In what the originality of the process
consists, in view of Deville's publications and even in view of
the processes just mentioned, we cannot see. Col. Frishmuth
himself admitted, in 1887, having abandoned the sodium process,
as the difficulties of the method did not permit its competing
with the more roundabout but more easily-conducted operation
with solid sodium. A simple transcript of the claims in his
patent will give a sufficiently extended idea of the reactions
proposed to be used.
1. The simultaneous generation of sodium vapor and a vola-
tile compound of aluminium in two separate vessels or retorts,
and mingling the vapors thus obtained in a nascent ( ! ) state
in a third vessel, wherein they react on each other.
2. The sodium vapor is produced from a mixture of a sodium
compound and carbon, or some other reducing agent; and the
aluminous vapor from aluminous material.
3. The simultaneous generation of sodium vapor and vapor
of aluminium chloride or aluminium fluoride; or of sodium
vapor and aluminium-sodium chloride.
* English patents 1995 and 493° (1883); German patent 27,572 (1884).
2 70 ALUMINIUM.
4. Converting the aluminous material to a vapor by heating
it in a retort with sodium chloride, and subjecting it at the
same time to chlorine gas ; mingling the vapor of aluminium-
sodium chloride thus obtained with vapor simultaneously gen-
erated from sodium carbonate and carbon.
H. von Grousillier' s Improvement (1885)-
This suggestion as to the way of performing the reduction
by sodium is the subject of the English patent 7858, June 29,
18B5. Dr. Fischer remarks on it, in " Wagner's Jahresbericht"
for 1885, that "it is apparently wholly worked out at the
writing-table," The patentee. Hector von Grousillier, Springe,
Hanover, thus describes his invention :
" In order to avoid the difficulties ordinarily met with in the
use of aluminium-sodium chloride to obtain aluminium, I raise
the volatilizing point of aluminium chloride by performing its
reduction, either chemically or electrolytically, under pressure
in a strong hermetically-closed vessel, lined with clay or mag-
nesia, and provided with a safety valve."
The Deville-Castner Process (1886).
This last development of the old Deville process was ope-
rated by the Aluminium Company, Limited, at their large new
works at Oldbury, near Birmingham, England. The plant
covered nearly five acres of ground, and adjoined Chance Bros.'
large chemical works, from which the hydrochloric acid used
was obtained and the waste soda-liquors returned, by means of
large pipes connecting the two plants. The company was thus
in position to obtain acid and dispose of its by-products to
very good advantage. The principle on which the process was
worked is similar to its predecessor, in being the reduction of
aluminium-sodium chloride by sodium, but it improves on the
other in the cheaper production of both these materials. For
instance, the alumina used is obtained and converted into
double chloride by Mr. Webster's processes, by which the cost
of this salt is not over 3^. per lb. (see p. 164), as against i2d..
REDUCTION OF ALUMINIUM COMPOUNDS. 2/1
the cost at Salindres ; further, by Mr. Castner's sodium process
it is acknowledged that the sodium cost only about ^d. per lb.,
as against 48^^., or $1, as formerly. Since 10 lbs. of the chlo-
ride and 3 lbs. of sodium are required to produce i lb. of alu-
minium, the average saving in these two items, over the old
process, is somewhere about 75 per cent.
The works contain a sodium building, in which are four large
sodium furnaces, each capable of producing over 500 lbs. of
that metal in twenty-four hours ; the sodium is also remelted
and stored in the same building (see p. 215). The double
chloride furnaces are in a building 250 feet by 50 feet wide, there
being 12 furnaces, each containing 5 retorts. The total output
of double chloride is an average of 5000 lbs. per day. (See. p.
162). Connected with this building is a chlorine plant of the
largest size, capable of supplying about a ton and a half of
chlorine a day. In a separate building are two reverberatory
furnaces, in which the final reduction takes place and the alu-
minium is produced. Besides these there are a rolling mill,
wire mill, and foundry on the grounds. From the quantity of
sodium and double chloride produced, we can see that the
works can produce about 500 lbs. of aluminium a day, or
150,000 lbs. a year, with some sodium left over for sale or other
purposes.
The mode of conducting the reduction is not very different
from that practiced at Salindres. There are two regenerative
reverberatory furnaces used, one about twice as large as the
other. The larger furnace has a bed about six feet square, slop-
ing towards the front of the furnace, through which are several
openings at different heights. The charge for this furnace con-
sists of 1200 lbs. of double chloride, 350 lbs. of sodium, and
600 lbs. of cryolite for a flux. The chloride is in small pieces,
the cryolite is in powder, and the sodium is cut into thin slices
by a machine. These ingredients are put into a revolving
wooden drum placed on a staging over the furnace, and are
there thoroughly mixed. The drum is then opened and
turned, when the contents fall into a small wagon beneath.
272 ALUMINIUM.
The furnace having been raised to the required temperature, all
the dampers are shut and the car is moved on a track immedi-
ately over a. large hopper placed in the roof of the furnace.
The hopper being opened, the charge is dumped in and drops
on to the centre of the hearth. The reaction is immediate,
and the whole charge becomes liquid in a very short time.
After a few minutes, heating gas is again turned on, and the
furnace kept moderately hot for two or three hours. The reac-
tion has been
AlCla.NaCl + 3Na = Al + 4NaCl
and the aluminium gathers under the bath of cryolite and sod-
ium chloride. One of the lower tap-holes is then opened with
a bar, and the aluminium run out into moulds. When the
metal has all run out it is followed by slag, which flows into
iron wagons. The openings are then plugged up and the fur-
nace is ready for another charge. The charge given produces
usually 115 to 120 lbs. of aluminium, the whole operation last-
ing about 4 hours. The large furnace could thus produce 840-
lbs. in 24 hours, and the smaller one half that quantity. The
first portion of metal running out is the purest, the latter por-
tions, and especially that entangled in the slag on the hearth, and
which has to be scraped out, containing more foreign sub-
stances. This impure metal is about one-fourth of all the
aluminium in the charge.
The purity of the metal run out depends directly on the
purity of the chloride used. If the double chloride contains
0.2 per cent, of iron, the metal produced will very probably
contain all of it, or 2 per cent. Using the double chloride
purified by Mr. Castner's new method (see p. 163), by which
the content of iron is reduced to 0.05 per cent, or less, alu-
minium can be made containing less than 0.5 per cent, of iron
and from 99 to 99.5 per cent, of aluminium. Professor Roscoe
exhibited at one of his lectures a mass of metal weighing 116'
lbs., being one single running from the furnace, and which con-
tained only 0.3 per cent, of silicon and 0.5 per cent. iron. In.
REDUCTION OF ALUMINIUM COMPOUNDS. 273
practice, the metal from 8 or 10 runnings is melted down to-
gether to make a uniform quality.
Taking the figures given, it appears that the metal run out
represents 70 per cent, of the aluminium in the charge, and 80
percent, of the weight which the sodium put in should reduce;
but since an indeterminate weight is sifted and picked from the
slag, it is probable that the utilization of the materials is more
perfect than the above percentages. However, this seems to
be the part of the old Deville process least improved upon in
these new works, for there seems to be plenty of room for im-
provement in perfecting the utilization of materials, especially
in regard to loss of sodium by volatilization, which undoubt-
edly takes place and which can possibly be altogether pre-
vented.
The above description, written in 1890, was followed only
one year later by the closing of this splendid works. The very
lowest point to which the Deville-Castner process could reduce
the cost of producing aluminium was between 4 and S shillings
per pound ; and when the metal was put on the market by users
of the electrolytic process at $1.50 per pound, in 1891, there
was nothing left for the sodium process except to give up the
business. The company, however, continues to run the works,
making and selling large quantities of sodium.
i8
CHAPTER X.
REDUCTION OF ALUMINIUM COMPOUNDS BY MEANS OF
POTASSIUM OR SODIUM {Continued).
II.
Methods based on the reduction of cryolite.
These can be most conveniently presented in chronological
order.
Rose's Experiments (1855).
We will here give H. Rose's entire paper, as an account of
this eminent chemist's investigations written out by himself
with great detail, describing failures as well as successes,
cannot but be of value to all interested in the production of
aluminium:*
" Since the discovery of aluminium by Wohler, Deville has
recently devised the means of procuring the metal in large, solid
masses, in which condition it exhibits properties with which we
were previously unacquainted in its more pulverulent form as
procured by Wohler's method. While, for instance, in the lat-
ter state it burns vividly to white earthy alumina on being ig-
nited, the fused globules may be heated to redness without
perceptibly oxidizing. These differences may be ascribed to
the greater amount of division on the one hand and of density
on the other. According to Deville, however, Wohler's metal
contains platinum, by which he explains its difficulty of fusion,
although it affords white alumina by combustion. Upon the
publication of Deville's researches, I also tried to produce
aluminium by the decomposition of aluminium-sodium chloride
by means of sodium. I did not, however, obtain satisfactory
* Pogg. Annalen, Sept., 1855.
(274)
REDUCTION OF ALUMINIUM COMPOUNDS. 2/5
results. Moreover, Prof. Rammelsberg, who followed exactly
the method of Deville, obtained but a very small product, and
found it very difficult to prevent the cracking of the glass tube
in which the experiment was conducted, by the action of the
vapor of sodium on aluminium chloride. It appeared to me
that a great amount of time, trouble and expense, as well as
long practice, was necessary to obtain even small quantities of
this remarkable metal.
" The employment of aluminium chloride and its compounds
with alkali chlorides is particularly inconvenient, owing to their
volatility, deliquescence, and to the necessity of preventing all
access of air during their treatment with sodium. It very soon
occurred to me that it would be better to use the fluoride of
aluminium instead of the chloride ; or rather the combination
of the fluoride with alkaline fluorides, such as we know them
through the investigations of Berzelius, who pointed out the
strong affinity of aluminium fluoride for sodium fluoride and
potassium fluoride, and that the mineral occurring in nature
under the name of cryolite was a pure compound of aluminium
fluoride and sodium fluoride.
" This compound is as well fitted for the preparation of
aluminium by means of sodium as aluminium chloride or
aluminium-sodium chloride. Moreover, as cryolite is not vola-
tile, is readily reduced to the most minute state of division, is
free from water and does not attract moisture from the air, it
affords peculiar advantages over the above-mentioned com-
pounds. In fact, I succeeded with much less trouble in pre-
paring aluminium by exposing cryolite together with sodium
to a strong red heat in an iron crucible, than by using alu-
minium chloride and its compounds. But the scarcity of cryo-
lite prevented my pursuing the experiments. In consequence
of receiving, however, from Prof. Krantz, of Bonn, a consider-
able quantity of the purest cryolite at a very moderate price
($2 per kilo), I was enabled to renew the investigation.
" I was particularly stimulated by finding, most unexpect-
edly, that cryolite was to be obtained here in Berlin commer-
2/6 ALUMINIUM.
cially at an inconceivably low price. Prof. Krantz had already
informed me that cryolite occurred in commerce in bulk, but
could not learn where. Shortly after, M. Rudel, the manager
of the chemical works of H. Kunheim, gave me a sample of a
coarse white powder, large quantities of which were brought
from Greenland by way of Copenhagen to Stettin, under the
name of mineral soda, and at the price of $3 per centner.
Samples had been sent to the soap boilers, and a soda-lye
had been extracted from it by means of quicklime, especially
adapted to the preparation of many kinds of soap, probably from
its containing alumina. It is a fact, that powdered cryolite is
completely decomposed by quicklime and water. The fluoride
of lime formed contains no alumina, which is all dissolved by the
caustic soda solution ; and this, on its side, is free from fluor-
ine, or only contains a minute trace. I found this powder to
be of equal purity to that received from Prof. Krantz. It dis-
solved without residue in hydrochloric acid (in platinum ves-
sels) ; the solution evaporated to dryness with sulphuric acid,
and heated till excess of acid was dissipated, gave a residue
which dissolved completely in water, with the aid of a little
hydrochloric acid. From this solution, ammonia precipitated
a considerable quantity of alumina. The solution filtered from
the precipitate furnished, on evaporation, a residue of sulphate
of soda, free from potash. Moreover, the powder gave the
well-known reactions of fluorine in a marked degree. This
powder was cryolite of great purity : therefore the coarse pow-
der I first obtained was not the form in which it was originally
produced. It is now obtainable in Berlin in great masses ; for
the preparation of aluminium it must, however, be reduced to a
very fine powder.
" In my experiments on the preparatipn of aluminium, which
were performed in company with M. Weber, and with his most
zealous assistance, I made use of small iron crucibles, i ^
inches high and i^ inches upper diameter, which I had cast
here. In these I placed the finely divided cryolite between
thin layers of sodium, pressed it down tight, covered it with a
REDUCTION OF ALUMINIUM COMPOUNDS. 277
good layer of potassium chloride (KCl), and closed the cruc-
ible with a well-fitting porcelain cover. I found potassium
chloride the most advantageous flux to employ ; it has the low-
est specific gravity of any which could be used, an important
point when the slight density of the metal is taken into consid-
eration. It also increases the fusibility of the sodium fluoride.
I usually employed equal weights of cryolite and potassium
chloride, and for every five parts of cryolite two parts of so-
dium. The most fitting quantity for the crucible was found to
be ten grammes of powdered cryolite. The whole was raised
to a strong red heat by means of a gas-air blowpipe. It was
found most advantageous to maintain the heat for about half an
hour, and not longer, the crucible being kept closely covered
the whole time ; the contents were then found to be well fused.
When quite cold the melted mass is removed from the crucible
by means of a spatula ; this is facilitated by striking the outside
with a hammer. The crucible may be employed several times,
at last it is broken by the hammer blows. The melted mass is
treated with water, when at times only a very minute evolution
of hydrogen gas is observed, which has the same unpleasant
odor as the gas evolved during solution of iron in hydrochloric
acid. The carbon contained in this gas is derived from a very
slight trace of naphtha adhering to the sodium after drying it.
On account of the difficult solubility of sodium fluoride, the
mass is very slowly acted on by water, although the insolubility
is somewhat diminished by the presence of the potassium chlo-
ride. After twelve hours the mass is softened so far that it
may be removed from the liquid and broken down in a porce-
lain mortar. Large globules of aluminium are then discovered,
weighing from 0.3 to 0.4 or even 0.5 grammes, which may be
separated out. The smaller globules cannot well be separated
from the undecomposed cryolite and the alumina always pro-
duced by washing, owing to their being specifically lighter than
the latter. The whole is treated with nitric acid in the cold.
The alumina is not dissolved thereby, but the little globules
then first assume their true metallic lustre. They are dried and
278 ALUMINIUM.
rubbed on fine silk muslin ; the finely powdered, undecom-
posed cryolite and alumina pass through, while the globules
remain on the gauze. The mass should be treated in a plati-
num or silver vessel; a porcelain vessel would be powerfully
acted on by the sodium fluoride. The solution, after standing
till clear, may be evaporated to dryness in a platinum capsule,
in order to obtain the sodium fluoride, mixed however with
much potassium chloride. The small globules may be united
by fusion in a small well-covered porcelain crucible, under a
layer of potassium chloride. They cannot be united without a
flux. They cannot be united by mere fusion, like globules of
silver, for instance, for though they do not appear to oxidize
on ignition in the air, yet they become coated with a scarcely
perceptible film of oxide, which prevents their running together
into a mass. This fusion with potassium chloride is always at-
tended with a loss of aluminium. Buttons weighing 0.85
gramme lost, when so treated, 0.05 gramme. The potassium
chloride when dissolved in water left a small quantity of alu-
mina undissolved, but the solution contained none. Another
portion of the metal had undoubtedly decomposed the potas-
sium chloride ; and a portion of this salt and aluminium chlo-
ride must have been volatilized during fusion (other metals, as
copper and silver, behave in a similar manner — Pogg. Ixviii.
287). I therefore followed the instructions of Deville, and
melted the globules under a stratum of aluminium-sodium chlo-
ride in a covered porcelain crucible. The salt was melted first,
and 'then the globules of metal added to the melted mass.
There is no loss, or a very trifling one of a few milligrammes of
metal, by this proceeding. When the aluminium is fused
under potassium chloride its surface is not perfectly smooth,
but exhibits minute concavities ; with aluminium-sodium chlo-
ride this is not the case. The readiest method of preparing
the double chloride for this purpose is by placing a mixture of
alumina and carbon in a glass tube, as wide as possible, and
inside this a tube of less diameter, open at both ends, and con-
taining sodium chloride. If the spot where the mixture is
REDUCTION OF ALUMINIUM COMPOUNDS. 279
placed be very strongly heated, and that where the sodium
chloride is situated, more moderately, while a current of chlo-
rine is passed through the tube, the vapor of aluminium chlo-
lide is so eagerly absorbed by the sodium chloride that none
or at most a trace is deposited in any other part of the tube.
If the smaller tube be weighed before the operation, the
amount absorbed is readily determined. It is not uniformly
combined with the sodium chloride, for that part which is near-
est to the mixture of charcoal and alumina will be found to
have absorbed the most.
" I have varied in many ways the process for the preparation
of aluminium, but in the end have returned to the one just de-
scribed. I often placed the sodium in the bottom of the cruci-
ble, the powdered cryolite above it, and the potassium chloride
above all. On proceeding in this manner, it was observed that
much sodium was volatilzed, burning with a strong yellow
flame, which never occurred when it was cut into thin slices and
placed in alternate layers with the cryolite, in which case the
process goes on quietly. When the crucible begins to get red
hot, the temperature suddenly rises, owing to the commence-
ment of the decomposition of the compound ; no lowering of the
temperature should be allowed, but the heat should be steadily
maintained, not longer, however, than half an hour. By pro-
longing the process a loss would be sustained, owing to the
action of the potassium chloride on the aluminium. Nor does
the size of the globules increase on extending the time even to
two hours : this efifect can only be produced by obtaining the
highest possible temperature. If the process be stopped, how-
ever, after five or ten minutes of very strong heat, the produc-
tion is very small, as the metal has not had sufficient time
to conglomerate into globules, but is in a pulverulent form and
burns to alumina during the cooling of the crucible. No ad-
vantage is gained by mixing the cryolite with a portion of
chloride before placing it between the layers of sodium, neither
did I increase the production by using aluminium sodium
chloride to cover the mixture instead of potassium chloride. I
28o ALUMINIUM.
repeatedly employed decrepitated sodium chloride as a flux in the
absence of potassium chloride, without remarking any important
difference in the amount of metal produced, although a higher
temperature is in this case required. The operations may also
be conducted in refractory unglazed crucibles made of stone-
ware, and of the same dimensions, although they do not resist so
well the action of the sodium fluoride at any high heats, but fuse
in one or more places. The iron crucibles fuse, however,
when exposed to a very high temperature in a charcoal fire.
The product of metal was found to vary very much, even when
operating exactly in the manner recommended, and with the
same quantities of materials. I never succeeded in reducing the
whole amount of metal contained in the cryolite (which con-
tains 13 per cent, of aluminium). By operating on 10
grammes of cryolite, the quantity I always employed in the
small iron crucible, the most successful result was 0.8 grm. But
0.5 or even 0.4 grm. may be considered favorable ; many times
I obtained only 0.3 grm., or even less. These very different
results depend on various causes, more particularly, however,
on the degree of heat obtained. The greater the heat, the
greater the amount of large globules, and the less amount of
minutely divided metal to oxidize during the cooling of the
crucible. I succeeded once or twice in reducing nearly the
whole of the metal to one single button weighing 0.5 grm., at
a very high heat in a stoneware crucible. I could not always
obtain the same heat with the blowpipe, as it depended in some
degree on the pressure in the gasometer in the gas-works,
which varies at different hours of. the day. The following ex-
periment will show how great the loss of metal may be owing
to oxidation during the slow cooling of the crucible and its con-
tents: In a large iron crucible were placed 35 grms. of cryolite
in alternate layers with 14 grms. of sodium, and the whole cov-
ered with a thick stratum of potassium chloride. The crucible,
covered by a porcelain cover, was placed in a larger earthen
one also covered, and the whole exposed to a good heat in a
draft furnace for one hour, and cooled as slowly as possible.
REDUCTION OF ALUMINIUM COMPOUNDS. 28 1
The product in this case was remarkably small, for O.135 grm.
of aluminium was all that could be obtained in globules. The
differences in the amounts reduced depend also in some degree
on the more or less successful stratification of the sodium
with the powdered cryolite, as much of the latter sometimes
escapes decomposition. The greater the amount of sodium
employed, the less likely is this to be the case ; however, owing
to the great difference in their prices, I never employed more
than 4 grms. of sodium to 10 grms. of cryolite. In order to
avoid this loss by oxidation I tried another method of prepara-
tion : Twenty grms. of cryolite were heated intensely in a gun-
barrel in a current of hydrogen, and then the vapor of 8 grms.
of sodium passed over it. This was effected simply by placing
the sodium in a little iron tray in a part of a gun-barrel without
the fire, and pushing it forward when the cryolite had attained
a maximum temperature. The operation went on very well,
the whole being allowed to cool in a current of hydrogen.
After the treatment with water, in which the sodium fluoride
dissolved very slowly, I obtained a black powder consisting for
the most part of iron. Its solution in hydrochloric acid gave
small evidence of aluminium. The small amounts I obtained,
however, should not deter others from making these experi-
ments. These are the results of first experiments, on which I
have not been able to expend much time. Now that cryolite
can be procured at so moderate a price, and sodium by De-
ville's improvements will in future become so much cheaper, it
is in the power of every chemist to engage in the preparation of
aluminium, and I have no doubt that in a short time methods
M'ill be found affording a much more profitable result.
" To conclude, I am of opinion that cryolite is the best
adapted of all the compounds of aluminium for the preparation
of this metal. It deserves the preference over aluminium-sodium
chloride or aluminium chloride, and it might still be employed
with great advantage even if its price were to rise considerably.
The attempts at preparing aluminium direct from alumina have
as yet been unattended with success. Potassium and sodium
282 ALUMINIUM.
appear only to reduce metallic oxides when the potash and
soda produced are capable of forming compounds with a por-
tion of the oxide remaining as such. Pure potash and soda,
with whose properties we are very slightly acquainted, do not
appear to be formed in this case. Since, however, alumina
combines so readily with the alkalies to form aluminates, one
would be inclined to believe that the reduction of alumina by^
the alkali metals should succeed. But even were it possible to^
obtain the metal directly from alumina, it is very probable that
cryolite would long be preferred should it remain at a moderate
price, for it is furnished by nature in a rare state of purity, and
the aluminium is combined in it with sodium and fluorine only,
which exercise no prejudicial influence on the properties of the
metal, whereas alumina is rarely found in nature in a pure state
and in a dense, compact condition, and to prepare it on a large
scale, freeing it from those substances which would act injuri-
ously on the properties of the metal, would be attended with
great difficulty.
" The buttons of aluminium which I have prepared are so
malleable that they may be beaten and rolled out into the
finest foil without cracking on the edges. They have a strong
metallic lustre. Some small pieces, not globular, however,
were found in the bottom of the crucible, and occasionally ad-
hering to it, which cracked on being hammered, and were dif-
ferent in color and lustre from the others. They were evi-
dently not so pure as the greater number of globules, and con-
tained iron. On sawing through a large button weighing 3.8
grammes, it could readily be observed that the metal for abotit
half a line from the exterior was brittle, while in the interior it
was soft and malleable. Sometimes the interior of a globule
contained cavities. With Deville, I have occasionally observed
aluminium crystallized. A large button became striated and
crystalline on cooling. Deville believes he has observed reg-
ular octahedra, but does not state this positively. According
to my brother's examination, the crystals do not belong to any
of the regular forms. As I chanced on one occasion to attempt
REDUCTION OF ALUMINIUM COMPOUNDS. 283
the fusion of a large, flattened- out button of rather impure
aluminium, without a flux, I observed, before the heat was suffi-
cient to fuse the mass, small globules sweating out from the
surface. The impure metal being less fusible than pure metal,
the latter expands in fusing and comes to the surface."
Experiments of Percy and Dick (1855).
After the publication of Rose's results, widespread attention
was directed toward this field, and it was discovered that some
six months previously Dr. Percy, in England, had accomplished
almost similar results, and had even shown a specimen of the
metal to the Royal Institution, but with the singular fact of ex-
citing very little attention. These facts are stated at length in
the following paper written by Allan Dick, Esq., which ap-
peared in November, 1855, two months after the publication of
H. Rose's paper: — *
" In the last number of this magazine was the translation of a
paper by H. Rose, of Berlin, describing a method of preparing
aluminium from cryolite. Previously, at the suggestion of Dr.
Percy, I had made some experiments on the same subject in
the metallurgical laboratory of the School of Mines ; and as the
results obtained agree very closely with those of Mr. Rose, it
may be interesting to give a short account of them now, though
no detailed description was published at the time, a small piece
of metal prepared from cryolite having simply been shown at
the weekly meeting of the Royal Institution, March 30, 1855,
accompanied by a few words of explanation by Faraday.
" Shortly after the publication of Mr. Deville's process for
preparing aluminium from aluminium chloride, I tried along
with Mr. Smith to make a specimen of the metal, but we found
it much more difficult to do than Deville's paper had led us to
anticipate, and had to remain contented with a much smaller
piece of metal than we had hoped to obtain. It is, however,
undoubtedly only a matter of time, skill, and expense to join
* Phil. Mag., Nov. 1855.
284 ALUMINIUM.
successful practice with the details given by Deville. Whilst
making these experiments, Dr. Percy had often requested us to
try whether cryolite could be used instead of the chlorides, but
some time elapsed before we could obtain a specimen of the
mineral. The first experiments were made in glass tubes
sealed at one end, into which alternate layers of finely powdered
cryolite and sodium cut into small pieces were introduced, and
covered in some instances with a layer of cryolite, in others by
sodium chloride. The tube was then heated over a gas blow-
pipe for a few minutes till decomposition had taken place, and
the product was melted. When cold, on breaking the tube, it
was found that the mass was full of small globules of aluminium,
but owing to the specific gravity of the metal and flux being
nearly alike, the globules had not collected into a button
at the bottom. To effect this, long-continued heat would be
required, which cannot be given in glass tubes owing to the
powerful action of the melted fluoride on them. To obviate
this difficulty, a platinum crucible was lined with magnesia
by ramming it in hard and subsequently cutting out all but
a lining. In this, alternate layers of cryolite and sodium were
placed, with a thickish layer of cryolite on top. The cruci-
ble was covered with a tight-fitting lid, and heated to redness
for about half an hour over a gas blowpipe. When cold it was
placed in water, and after soaking for some time the contents
were dug out, gently crushed in a mortar, and washed by de-
cantation. Two or three globules of aluminium, tolerably large
considering the size of the experiment, were obtained, along
with a large number of very small ones. The larger ones were
melted together under potassium chloride. Some experiments
made in iron crucibles were not attended with the same success
as those of Rose : no globules of any considerable size re-
mained in the melted fluorides ; the metal seemed to alloy on
the sides of the crucible, which acquired a color like zinc. It
is possible that this difference may have arisen from using a
higher temperature than Rose, as we made these experiments
in a furnace, not over the blowpipe. Porcelain and clay cru-
REDUCTION OF ALUMINIUM COMPOUNDS. 285
cibles were also tried, but laid aside after a few experiments,
owing to the action of the fluorides upon them, which in most
cases was sufificient to perforate them completely."
Deville's Methods (1856-8).
* " I have repeated and confirmed all the experiments of Dr.
Percy and H. Rose, using the specimens of cryolite which I
obtained from London through the kindness of MM. Rose and
Hofmann. I have, furthermore, reduced cryolite mixed with
sodium chloride by the battery, and I believe that this will be
an excellent method of covering with aluminium all the other
metals, copper in particular. Anyhow, its fusibility is consid-
erably increased by mixing it with aluminium-sodium chloride.
Cryolite is a double fluoride of aluminium and sodium, con-
taining 13 per cent, of aluminium and having the formula
AlFj.sNaF. I have verified these facts myself by many
analyses.
" In reducing the cryolite I placed the finely pulverized mix-
ture of cryolite and sodium chloride in alternate layers with
sodium in a porcelain crucible. The uppermost layer is of
pure cryolite, covered with salt. The mixture is heated just to
complete fusion, and after stirring with a pipe-stem, is let cool.
On breaking the crucible, the aluminium is often found united
in large globules, easy to separate from the mass. The metal
always contains silicon, which increases the depth of its natural
blue tint and hinders the whitening of metal by nitric acid, be-
cause of the insolubility of the silicon in that acid. M. Rose's
metal is very ferruginous. I have verified all M. Rose's ob-
servations, and I agree with him concerning the return of
metal, which I have always found very small. There are al-
ways produced in these operations brilliant flames, which are
observed in the scoria floating on the aluminium, and which
are due to the gas burning and exhaling a very marked odor
of phosphorus. In fact, phosphoric acid exists in cryolite, as
* Ann. de Chim. et de Phys. [3], xlvi. 451.
286 ALUMINIUM.
one may find by treating a solution of the mineral in sulphuric
acid with molybdate of ammonia, according to H. Rose's re-
action.
" M. Rose has recommended iron vessels for this operation,
because of the rapidity with which alkaline fluorides attack
earthen crucibles and so introduce considerable silicon into the
metal. Unfortunately, these iron crucibles introduce iron into
the metal. This is an evil inherent in this method, at least in
the present state of the industry. The inconveniences of this
method result in part from the high temperature required to
complete the operation, and from the crucible being in direct
contact with the fire, by which its sides are heated hotter than
the metal in the crucible. The metal itself, placed in the lower
part of the fire, is hotter than the slag. This, according to my
observations, is an essentially injurious condition. The slag
ought to be cool, the metal still less heated, and the sides of
the vessel where the fusion occurs ought to be as cold as pos-
sible. The yield from cryolite, according to Rose's and my own
observations, is also very small. M. Rose obtained from lo of
cryolite and 4 of sodium about 0.5 of aluminium. This is due
to the affinity of fluorine for aluminium, which must be very
strong not only with relation to its affinity for sodium, but even
for calcium, and this affinity appears to increase with the tem-
perature, as was found in my laboratory. Cryolite is most
convenient to employ as a flux to add to the mixture which is
fused, especially when operating on a small scale.
"The argument which decided the company at Nanterre not
to adopt the method of manufacture exclusively from cryolite
was the report of M. de Chancourtois, mining engineer, who
had just returned from a voyage to Greenland. According to
the verbal statements of this gentleman, the gite at Evigtok is
accessible only during a very short interval of time each year,
and, because of the ice fields, can only be reached then by a
steamboat. The workmen sent from Europe to blast and load
up the rock have scarcely one or two months of work possible.
The local workmen remain almost a whole year deprived of all
REDUCTION OF ALUMINIUM COMPOUNDS. 287
communication with the rest of the world, without fresh provi-
sions or fuel other than that brought from Europe in the short
interval that navigation is open. The deposit itself, which is
scarcely above sea-level, can be easily worked with open roof,
but the neighborhood of the sea in direct contact with the vein,
the unorganized manner of working, and the lack of care in
keeping separate the metalliferous portions of the ore — all com-
bine to render the mineral very costly, and further developments
underground almost impossible.
" It is therefore fortunate that cryolite is not indispensable,
for no one would wish to establish an industry based on the
employment of a material which is of such uncertain supply."
Tissier Bros.' Method (1857).
The process adopted in the works at Amfreville, near Rouen,
directed by Tissier Bros., is essentially that described by Percy
and Rose. The method of operating is given by the Tissier
Bros, themselves in their book as follows :
"After having finely powdered the cryolite, it is mixed with
a certain quantity of sodium chloride (sea salt), then placed be-
tweeen layers of sodium used in the proportions given by M.
Rose, in large refractory crucibles. These are heated either in
a reverberatory furnace or in a wind furnace capable of giving
a temperature high enough to melt the fluoride of sodium pro-
duced by the reaction. As the sodium fluoride requires a
pretty high temperature to fuse it, the heat will necessarily be
higher than that required in the reduction of the double
chloride of aluminium and sodium. When the contents of the
crucible are melted, so as to be quite liquid, the fusion is poured
into cast-iron pots, at the bottom of which the aluminium col-
lects in one or several lumps."
Tissier Bros, claimed the following advantages for the use of
cryolite :
" Cryolite comes to us of a purity difficult to obtain with the
double chloride of aluminium and sodium, to which it exactly
corresponds ; and since, thanks to the perfection we have at-
288 ALUMINIUM.
tained in using it, the return of aluminium is exactly correspon-
dent to the amount of sodium used in reduction, it is easily seen
what immense advantages result from its employment. The
double chloride deteriorates in the air, it gives rise in the works
to vapors more or less deleterious and corrosive, and its price
is always high. Cryolite can be imported into France at a
price so low that we have utilized it economically for making
commercial carbonate of soda ; it remains unaltered in the air,
emits no deleterious vapors, and its management is much more
easy than that of the double chloride. Moreover, on compar-
ing the residues of the two methods of reduction, the manufac-
ture from double chloride leaves sodium chloride, almost with-
out value, while the manufacture from cryolite leaves sodium
fluoride, which may be converted for almost nothing into
caustic soda or carbonate, and so completely cancels the cost
of the cryolite from the cost of aluminium. The most serious
objection which can be made to using cryolite is that the
sources of the mineral being up to the present very limited, the
future prospect of aluminium Hes necessarily in the utilization
of clays and their transformation into aluminium chloride ; but,
admitting that other sources of cryolite may not be discov-
ered hereafter, the abundance of those which exist in Greenland
will for a long time to come give this mineral the preference in
the manufacture of aluminium."
The most serious difhculty which this process had to meet,
and which it could not overcome, was the high content of sili-
con in the metal produced. A specimen of their aluminium
made in 1859 contained 4.4 per cent, of silicon alone (see p.
54, Analysis 7). The firm at Rouen went out of business about
1863 or 1865 — I am unable to give the exact date. From that
time until quite recently, it has been considered that the best
use of cryolite is as a flux in the preparation of aluminium from
aluminium-sodium chloride, in which case the slag is not sodium
fluoride, but aluminium fluoride, which acts but slightly on the
containing vessel.
REDUCTION OF ALUMINIUM COMPOUNDS. 289
Wohler' s Modifications (1856).
Wohler suggested the following modifications of Deville's
process of reducing cryolite in crucibles, by means of which
the reduction can be performed in an earthen crucible without
the metal produced taking up silicon.
*"The finely pulverized cryolite is mixed with an equal
weight of a flux containing 7 parts sodium chloride to 9 parts
potassium chloride. This mixture is then placed in alternate
layers with sodium in the crucible, 50 parts of the mixture to
10 of sodium, and heated gradually just to its fusing point.
The metal thus obtained is free from silicon, but only one-third
of the aluminium in the cryolite is obtained." In spite of the
small yield, this method was used for some time by Tissier
Bros.
Gerhard's Furnace (1858).
This furnace was devised for the reduction of aluminium
either from aluminium-sodium chloride or from cryolite, the
object being to prevent loss of sodium by ignition. It was in-
vented and patented by W. F. Gerhard. | " It consists of a
reverberatory furnace having two hearths, or of two crucibles,
or of two reverberatory furnaces, placed one above the other
and communicating by an iron pipe. In the lower is placed a
mixture of sodium with the aluminium compound, and in the
upper a stratum of sodium chloride, or of a mixture of this
salt and cryolite, or of the slag obtained in a previous ope-
ration. This charge, when melted, is made to run into the
lower furnace in quantity sufficient to completely cover the
mixture contained therein, and so to protect it from the air.
The mixture thus covered is reduced as by the usual operation."
Whether a furnace was ever put up and operated on this
principle, the author cannot say. It is possible that it may
have been used in the English manufactory started in 1859
at Battersea near London. (See p. 18.)
* Ann. der Chem. und Pharm. 99,255.
t Eng. Pat., 1858, No. 2247.
19
290 ALUMINIUM.
Thompson and White's Patent (1887).
* J. B. Thompson and W. White recommend heating a mix-
ture of 3 parts sodium and 4 parts cryolite to 100°, whereby
the sodium becomes pasty and the whole can be well kneaded
together with an iron spatula. When cold, 4 parts of alumin-
ium chloride are added, and the mixture put into a hopper on
top of a well-heated reverberatory furnace, with a cup-shaped
hearth. The charge is dropped into the furnace and the
reaction takes place at once. To produce alloys, this patent
claims 16 parts of cryolite are mixed with 5 parts of sodium,
the metal added before reduction and the mixture treated as
above, by which means explosions are avoided. The pre-
liminary heating to 100° is effected in a jacketed cast-iron pot
connected with a circulating boiler.
Hampe's Experiment (1888).
t Dr. W. Hampe failed to produce aluminium bronze by treat-
ing cryolite with sodium in the presence of copper. A mixture of
Finely divided copper 44 grammes,
Sodium, in small pieces, 15 "
Finely powdered cryolite 100 "
was melted rapidly in a carbon-lined crucible. There were no
sounds given out such as usually accompany other reductions
by sodium, but much sodium vapor was given off. The copper
button contained only traces of aluminium.
Netto's Process (1887).
Dr. Curt Netto, of Dresden, patented in England and Ger-
many, in spring and autumn of 1887, processes for producing
sodium and potassium and methods of using them in producing
aluminium. His experiments were made in conjunction with
Dr. Salomon, of Essen, and the fact that the experimental ap-
* English patent 8427, June 11, 1887.
tChemiker Zeitung, (Cothen), xii, p. 391.
REDUCTION OF ALUMINIUM COMPOUNDS. 29 1
paratus was put up in Krupp's large steel works at Essen gave
rise to reports that the latter had taken up the manufacture of
aluminium by some new and very successful process, intending
to use it for alloys in making cannon. *
In the latter part of 1888 was formed the Alliance Aluminium
Co. of London, England, capitalized at ;£'5oo,ooo, purposing to
manufacture sodium and aluminium, and owning the English,
French, German, and Belgian patents of Dr. Netto for the pro-
duction of those metals, also the processes of a Mr. Cunning-
ham for the same purpose, also a process for the production of
artificial cryolite by the regeneration of slag (provisionally pro-
tected by its inventor, Mr. Forster, of the Lonesome Chemical
Works, Streatham), and, lastly, a process invented by Drs.
Netto and Salomon by which aluminium can be raised to the
highest standards of purity on a commercial scale. A note
accompanying the above announcement stated that the exhaust-
ive experiments made at Essen had satisfactorily demonstrated
the practicability of the processes, and that the company had
already contracted with the cryolite mines of Greenland for all
the cryolite they would need.
In June, i888,t the Alliance Aluminium Company had in
operation a small aluminium plant at King's Head Yard, Lon-
don, E. C, and when the process was in continuous opera-
tion the cost of the metal was set down at 6 shillings per
pound. It is probable that the metal exhibited in the Paris
Exposition of 1889 was produced at this place.
In April, 1889,! ten acres of ground had been leased at
Hepburn on which to produce sodium by Capt. Cunningham's
process. The sodium produced was to be sent to Wallsend to
be used by the Alliance Aluminium Company, who were erect-
ing a large works at that place.
As for Capt. Cunningham's sodium processes, they are ap-
parently identical with Dr. Netto's. Cunningham's aluminium
♦American Register, Paris, August, 1888.
t Engineering, June i, 1888.
X E. and M. J., April 27, 1889.
292
ALUMINIUM.
process* consists in melting the sodium to be used with lead,
in order to facihtate the submerging of the sodium under the
molten aluminium salt. The alloy is cast into bars and added
piece by piece to the bath of molten aluminium salt on the
hearth of a reverberatory furnace. After the reaction the mix-
ture separates by specific gravity into lead, containing a little
aluminium, and aluminium containing a little lead, the slag
floating on top of all. Aluminium is known to have so small an
attraction for lead that this result becomes possible.
Fig. 26.
Dr. Netto recommends several processes, the one used at
London being the following: — |
One hundred parts of cryolite and 30 to 100 parts of sintered
sodium chloride are melted at a red heat in a well-covered clay
crucible. (Another arrangement, and apparently a better, is to
melt this mixture on the hearth of a reverberatory furnace and
tap it into a deep, conical ladle, in which the succeeding opera-
tions proceed as about to be described. See Fig. 26.) As soon
as the bath is well fused, 35 parts of sodium at the end of a rod, and
* English Patent, 16727, Dec. 5, 1887.
t German Patent (D. R. P.), 45198, March 26, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 293
covered over by a perforated concave plate is pushed quickly
down to the bottom of the crucible. The plate mentioned fits
across the whole section of the crucible at its lower part, so that
the fusible, easily volatile sodium, being vaporized, is divided into
very fine streams as it passes upwards through the bath, and is
all utilized before it reaches the surface. In this way the re-
action is almost instantaneous, and the contents can be poured
out at once into iron pots, where, on cooling, the metal is found
as a large lump at the bottom.
It is further observed that to avoid explosions on introducing
the sodium it should have in it no cavities which might contain
moisture or hydrocarbons. In consequence of the reaction be-
ing over so quickly, and the heat set free in the reduction, the
syrupy fusion becomes thin as water, and the aluminium dis-
seminated through the mass collects together completely, so
that the slag contains no particles visible to the eye. Since the
reduction, pouring, and cooling take place so quickly, the alu-
minium is not noticeably redissolved by the bath, thus insuring
a high return of metal. By using 35 parts of sodium to 100
parts of cryolite, 10 parts of aluminium are obtained. Since
the cryolite contains 13 per cent, of aluminium, the return is
yy per cent, of the amount of metal in the cryolite; since 35
parts of sodium should theoretically displace 14 parts of alu-
minium, the return is 71 per cent, of the amount which the
sodium should produce. Dr. Netto claims that this is double
the return formerly obtained from cryolite. The metal pro-
duced is said to be from 98.5 to 99 per cent. pure.
The apparatus erected at Krupp's works at Essen, which was
described by the newspapers as similar to a Bessemer converter,
was constructed and operated as follows : A large iron cylinder
is pivoted at the centre in a manner similar to a Bessemer con-
verter. Passing through the centre of the cylinder, longitudi-
nally, is a large iron tube in which generator gas is burnt to
heat the vessel.. To heat it up, it is placed erect, connection
made with the gas-main, while a hood above connects with the
chimney. On top of the cylinder, a close valve communicates
294 ALUMINIUM.
with the interior, for charging, and at the other end is a tap-
hole. The charge of cryoHte being put in, the flame is passed
through the central tube until the mineral is well fused. Then
soHd or melted sodium is passed in at the top, the valve is
screwed tight, the gas shut off, and the whole cylinder is rotated
several times until reduction is complete, when it is brought
upright, the tap-hole opened and slag and metal tapped into a
deep iron pot, where they separate and cool. Aluminium thus
made could not but contain much iron, even up to 14 per cent.,
it is said, which would prevent its use for any purpose ex-
cept alloying with iron. To procure pure aluminium, the ves-
sel would have to be properly fettled.
Dr. Netto also devised an arrangement similar to Heaton's
apparatus for making steel. It consisted of a large, well-lined
vessel on trunnions, the bottom of which was filled to a certain
depth with sodium, then a perforated aluminium plate placed
like a false bottom over it. On pouring molten cryolite into
the vessel, the aluminium plate prevented the sodium from rising
en masse to the surface of the cryolite. After the reaction was
over, the vessel was tilted and the slag and metal poured out
into iron pots.
The modification of the crucible method appears to have
been the most feasible of Netto's processes, and was probably
that used at Wallsend by the Alliance Aluminium Com-
pany. Outside estimates of the cost of aluminium to this com-
pany placed it at $1.50 to $2 per pound. They were selling in
the latter part of 1889 at 11, 13, and 15 shillings per pound,
according to quality, but were forced out of the business by the
electrolytic processes in 189 1.
Grabau's Process (1887).
There is only one patentee claiming particularly the reduc-
tion of aluminium fluoride by sodium — Ludwig Grabau, of
Hannover, Germany. His patents on this subject are im-
mediately preceded by others on a method of producing the
aluminium fluoride cheaply, which are described on p. 171, and
REDUCTION OF ALUMINIUM COMPOUNDS. 295
the inventor has patented a process which will furnish him with
cheap sodium. Mr. Alexander Siemens is authority for the
statement that a plant was in operation in the spring of 1889,
in Hannover, producing aluminium by this process on a com-
mercial scale. The principal object of Mr. Grabau's endeavors
has been to produce metal of a very high degree of purity. To
this end every precaution is taken to procure pure materials
and to prevent contamination during reduction. We will quote
from a paper written by Mr. Grabau* and also from his speci-
fications,f the following explanation of the process :
" The purifying of impure aluminium is accompanied by so
many difficulties that it appears almost impossible. It is there-
fore of the greatest importance to so conduct the operation that
every impurity is excluded from the start. Molten aluminium
compounds, whether a flux is added or not, attack any kind of
refractory vessels and become siliceous if these vessels are made
of chamotte or like materials, or if made of iron they become
ferruginous. These impurities are reduced in the further pro-
cesses and pass immediately into the aluminium as iron, silicon,
etc. Evidently the case is altered if an aluminium compound
which is infusible can be used advantageously. Aluminium
fluoride is infusible and also retains its pulverized condition
when heated up to the temperature needed for its use ; it can
therefore be heated in a vessel of any kind of refractory mater-
ial, or even in a metallic retort, without danger of taking up any
impurity.
" Further, it is necessary for succeeding in producing alu-
minium that the reduced metal thall unite to a large body after
the reduction. For this purpose all previous processes use
fluxes, and usually cryolite. But cryolite is impure, and there-
fore here is a source of many of the impurities in commercial
aluminium. Dr. K. Kraut, of Hannover, has observed that,
according to the recent analyses of Fresenius and Hintz, com-
* Zeitschrift fur angewandte, Chemie, 1889, vol. 6.
t German Pat. (D. R. P.) 47°3'. Nov. 15, 1887. English Pat. 15593, Nov. 14,
1887. U. S. Patents 386704, July 24, l888; and 400449, April 2, 1889.
296 ALUMINIUM.
mercial cryolite contains 0.80 to 1.39 per cent, of silicon, and
o.ii to 0.88 per cent, of iron, and that these impurities inter-
penetrate the mineral in such a manner as to be often only vis-
ible under the microscope, and therefore totally impossible of
removal by mechanical means. It is thus seen that the avoid-
ance of the use of any Rux is of great importance as far as
producing pure metal is concerned, as well as from an eco-
nomic standpoint.
" By the following process it is also possible to reduce alu-
minium fluoride by ?odium without the vessel in which reduc-
tion takes place being attacked either by the aluminium-sodium
fluoride formed or by the reduced aluminium. For this pur-
pose the aluminium fluoride and sodium are brought together
in such proportions that after the reaction there is still suffi-
cient aluminium fluoride present to form with the sodium flu-
oride resulting from the reaction a compound having the com-
position of cryolite. The reaction, therefore, will be
2AlF3-h3Na=Al-l-AlF3.3NaF.
" Using these proportions, the aluminium fluoride must be
previously warmed up to about 600° C, in order that when it is
showered down upon the melted sodium the reaction may com-
mence without further application of heat. The aluminium
fluoride remains granular at this temperature and therefore re-
mains on top of the melted sodium, like saw-dust or meal upon
water, and under its protection the reaction proceeds from
below upwards — an important advantage over the usual method
of pouring molten aluminium compounds on to sodium, in
which the lighter sodium floats to the top and burns to waste.
If solid sodium is used in my process the aluminium fluoride
must be somewhat hotter on being poured into the reduction
vessel, or about 700° C. For carrying out the process the re-
duction vessel must be artificially cooled, so as to form a lining
by chilling some of the aluminium-sodium fluoride formed by
the reaction, on the inner walls. This lining is in no wise
further attacked by the contents of the vessel, nor can it evi-
dently supply to them any impurity.
REDUCTION OF ALUMINIUM COMPOUNDS.
297
Fig. 27.
298 ALUMINIUM.
"The furnace A (Fig. 27) with grate B and chimney C,
serves for heating the iron retorts D and E, which are coated
with chamotte and protected from the direct action of the flame
by brick work. The vessel D serves for heating the aluminium
fluoride, and is provided with a damper or sliding valve be-
neath. The sodium is melted in E, and can be emptied out by
turning the cock k. The water-jacketed reduction vessel is
mounted on trunnions to facilitate emptying it. The retorts
are first heated dark red-hot, and D is filled with the conven-
ient quantity of aluminium fluoride. When this has become
red hot, as is shown by a small quantity of white vapor is-
suing from it, the required quantity of sodium is put into E.
This melts very quickly, and is then immediately run into the
reduction vessel by opening the stop-cock k. As soon as it is
transferred, the slide at the base of the retort D is pulled out
and the whole quantitity of aluminium fluoride falls at once
upon the sodium, and the reaction begins. As before re-
marked, the granular form of the aluminium fluoride keeps it
on top of the sodium, so that the latter is completely covered
during the whole reaction. This prevents almost altogether
any waste of sodium by volatilization. Dr. K. Kraut testifies
to an operation which he witnessed in which the return showed
83 per cent, of the sodium to have been utilized. An efficiency
in this respect of over 90 per cent, has been occasionally
reached, while the average is 80 to 90. Ad. Wurtz states that
the average for several years' working of the Deville process
showed only 74.3 per cent, of the quantity of aluminium pro-
duced which the sodium used could have given.
"During the reaction a very high temperature is developed,
so that the cryolite formed becomes very fluid, but is chilled
against the sides of the vessel to a thickness of a centimetre or
more. This crust is a poor conductor of heat, and is neither
attacked by the fluid cryolite nor by the aluminium. In con-
sequence of the great fluidity of the bath, it is possible for the
aluminium to unite into a body without the use of any flux,
The reaction being over, which is accomplished with the above
REDUCTION OF ALUMINIUM COMPOUNDS. 299
proportions of materials in a few seconds, and the vessel hav-
ing been shaken briskly backwards and forwards a few times to
facilitate the settling of the aluminium, the whole is turned on
the trunnions and emptied into a water-jacketed iron pot, where
it cools. The crust of cryolite inside the reduction vessel is
left there, and the apparatus is ready for another operation."
M. Grabau, in a private communication to the author, sums
up the advantages of his process, including the production of
the aluminium fluoride, as follows : —
1. The process is not dependent on natural cryolite, which is
expensive, impure and not easily purified.
2. The raw material — aluminium sulphate — can be procured
in large quantities and of perfect purity.
3. The aluminium fluoride is produced by a wet process,
which offers no difficulties to production on a large scale.
4. The fluorspar may be completely freed from foreign
metals by washing with dilute acid ; any silica present is not
injurious, as it remains undissolved in the residue during the
reactions.
5. The cryolite formed in each reduction contains no impur-
ities, and an excess of it is produced which can be sold.
6. The reduction of aluminium fluoride by my method gives
a utilization of 80 to 90 per cent, of the sodium used, which is
much more than can be obtained by other processes.
7. Aluminium fluoride is infusible, and can therefore be
heated in a vessel of any refractory material without taking up
any impurities. It is also unchanged in the air, and can be
kept unsealed for any length of time without deteriorating in
the least.
8. No flux has to be added for reduction, the use of impure
flux being a frequent cause of impurity of the metal.
In point of fact, M. Grabau has succeeded in producing sev-
eral hundred pounds of aluminium averaging over 99^ per
cent. pure. Dr. Kraut reports an analysis of an average speci-
men with 99.62 per cent, of aluminium (see Analysis 20, p. 54),
and metal has been made as pure as 99.8 per cent., a piece of
300 ALUMINIUM.
which has been kindly forwarded the author by M. Grabau, and
I freely admit it to be as fine a specimen of aluminium as I have
ever seen. Metal of such purity and fineness can only be made
by the electrolytic processes at considerable expense over ordi-
nary best commercial metal, since they must use chemically pure
alumina and extra precautions as to the purity of the electrodes.
It therefore appears possible that M. Grabau may yet be able
to manufacture and sell this extra quality aluminium, if he can
bring its price anywhere near that of the electrolytic aluminium.
The Grabau Aluminium Werke, Trotha, Germany, operates the
Grabau processes, and does a business in manufacturing and
selling sodium.
CHAPTER XI.
REDUCTION OF ALUMINIUM COMPOUNDS BY THE USE OF
ELECTRICITY.
As preliminary to the presentation of the various electrolytic
methods which have been proposed or , used, it may be profit-
able to review briefly the principles of electro-metallurgy as
they apply to the decomposition of aluminium compounds.
Some additional observations have been already included in
Chapter VIII.
The atomic weight of aluminium being 27, its chemical
equivalent, or the weight of it equal in consbining power to one
part of hydrogen, is 9. Therefore a current of quantity sufiS-
cient to liberate i part of hydrogen in a certain time would
produce 9 parts of aluminium in the same time, according to
the fundamental law of electric decomposition. It has been
determined that a current of i ampere acting for one second,
liberates 0.00001035 grammes of hydrogen; therefore it will
produce or set free from combination in the same time,
0.00009315 grammes of aluminium. This is the electro-chemical
equivalent of aluminium. Now, from thermo-chemical data we
know that the amount of energy required to set free a certain
weight of aluminium will vary with the compound from which
it is produced ; but the above equivalent is independent of the
compound decomposed, therefore there must be some varying
factor connected with the quantity of the current to account
for the different amounts of work which the current does in
decomposing diflferent compounds of the same element. This
is exactly in accordance with the principles of the mechanical
or thermal equivalent of the electric current, for the statement
" a current of one ampere," while it expresses a definite quan-
(301)
302 ALUMINIUM.
tity of electricity, yet carries no idea of the energy represented
by that current; we must know against what resistance or with
what electro- motive force that quantity is moved, and then we
can calculate its mechanical equivalent. Now, a current of i
ampere flowing against a resistance of i ohm, or in other
words, with a moving force or intensity of i volt, represents a
quantity of energy in one second equal to 0.00024 calories of
heat or to O.I kilogrammetre of work, and is therefore nearly
^ijf of a horse power. Therefore we can calculate the theoreti-
cal intensity of current necessary to overcome the affinities of
any aluminium compound for which we know the appropriate
thermal data. For instance, when aluminium forms its chlo-
ride (see p. 228) ^ — — — =5,960 calories are developed per
54
kilo of aluminium combining ; consequently the liberating of
0.00009315 grammes of aluminium (its electro-chemical equiva-
lent), requires the expenditure of an amount of energy equal to
0.00009315 X 5.960 = 0.000555 calories. Since a current of
I ampere at an intensity of i volt represents only 0.00024 cal-
ories, the intensity of current necessary to decompose alumin-
ium chloride is theoretically — '- — ^= 2.3 volts. In a simi-
0.00024
lar manner we can calculate that to decompose alumina would
, . ^. , , 391600 0.00000009315
require an electro-motive force of x Z^-^ =
54 0.00024
2.8 volts. These data would apply only to the substances
named, in a fused anhydrous state ; with hydrated aluminium
chloride in solution, a far. greater electro-motive force would be
necessary. If we had the thermal data we could also calculate
the intensity of current necessary to decompose the sulphate,
nitrate, acetate, etc., in aqueous solution; but failing these, we
can reason from analogy that it would be several volts in each
case.
It must be noted also, that these heats of combination are
those observed at ordinary temperatures. To find the voltage
required at high temperatures we must make allowance for the
REDUCTION OF ALUMINIUM COMPOUNDS. 303
weakening of the affinities, that is, for the decrease in heat of
combination as the temperature rises. When the rate of this
decrease is known, the true voltage required at any temperature
can be calculated. Often the operation is reversed ; that is, the
minimum electro-motive force required to effect decomposition
is accurately measured at different temperatures, and from
these data the variation in the heat of formation with the tem-
perature can be calculated by reversing the above calculations.
For example of this see p. 239.
To utilize such calculations, we must bear in mind exactly
what they represent. To decompose fused aluminium chloride,
for instance, not only must the current possess an intensity of
2.3 volts, but it must in addition have power enough above this
to overcome the transfer resistance of the electrolyte ; i. e., to
force the current through the bath from one pole to the other.
So, then, 2.3 volts would be the absolute minimum of intensity
which would produce decomposition, and the actual intensity
practically required would be greater than this, varying with
the distance of the poles apart and the temperature of the
bath as far as it affects the conducting power of the electrolyte.
From this it would immediately follow that if the substance to
be decomposed is an absolute non-conductor of electricity, no
intensity of current will be able to decompose it. If, on the
other hand, the substance is a conductor and the poles are
within reasonable distance, a current of a certain intensity will
always produce decomposition. The objection is immediately
made that in most cases no metal is obtained at all, which is
true not because none is produced, but because it is often dis-
solved by secondary actions as quickly as it is produced. I
need but refer to the historic explanation of the decomposition
of caustic soda in aqueous solution, although we have cases
hardly parallel to this in which the electrolyte itself dissolves
the separated metal.
How about the case of aqueous solutions ? Water requires a
minimum electro-motive force of 1.5 volts to decompose it,
and hence a prominent electrician remarked of a compound
304 ALUMINIUM.
which theoretically required over 2 volts that its decomposition
in aqueous solution would involve the decomposition of the
water and therefore was impossible. This remark is only partly
true ; for caustic soda requres over 2 volts, yet if mercury is
present to absorb the sodium as it is set free and protect it from
the water, we will obtain sodium, while the water is decomposed
at the same time. The truth seems to be that if two substances
are present which require different electro-motive forces to de-
compose them, a current of a certain intensity will decompose
the one requiring the least force, without affecting the other at
all; but, if it is of an intensity sufficient to decompose the
higher compound, then the current will be divided in some ratio
between the two, decomposing them both. This theory would
render theoretically possible the decomposition of aluminium
salts in aqueous solution, with a waste of power proportional to
the amount of water decomposed at the same time ; but
whether any aluminium would be obtained would be contingent
on the secondary action of the water on the aluminium. Pure
aluminium in mass is not acted upon by water, but the foil is
rapidly eaten away by boihng water. The state of division of
the metal, then, determines the action of water on it, and it is
altogether probable that the reason why aluminium is not easily
deposited from aqueous solution is that, like sodium, it is
attacked as soon as isolated, the acidity of the solution convert-
ing the hydrate formed back into the salt, or else simply the
hydrate remaining. Unfortunately, mercury does not exercise
the same function with aluminium as with sodium, for water at-
tacks its amalgam with aluminium, and so destroys the metal.
It is possible that if some analogous solvent could be found which
protected the aluminium from the action of water, the deposi-
tion from aqueous solution could be performed quite easily.
The electro-deposition of a metal using a soluble anode is
entirely a different affair. In this case, while the salt in solu-
tion is decomposed, yet it is immediately regenerated by the
acid radical set free dissolving from the anode just the same
quantity of metal as was deposited at the cathode. This action
REDUCTION OF ALUMINIUM COMPOUNDS. 3OS
exactly counterbalances the electromotive force required for
decomposition, and leaves only the conduction resistance of the
bath to be overcome. If this resistance is kept down so that
the tension required to operate the bath is less than or not
much greater than 1.5 volts, and the bath is well supplied with
salt, there will be no water decomposed and a good plating
may be obtained. This has been already practised on a large
scale with aluminium.
With anodes, however, which do not dissolve, the decom-
position of the salt necessarily involves that of the water, if over
1.5 volts are required to decompose it. The result of this is
that hydrogen gas is set free liberally at the cathode along with
the metal, and prevents the latter from depositing as a smooth,
dense metal, causing, in fact, the production of "sponge."
This finely-divided spongy metal is in the very best condition
to decompose water, and the result is its oxidation. However,
the metal can only decompose water at a certain rate ; the oxi-
dation does not take place instantaneously. If then we de-
posit the metal faster than it can waste away by oxidation, by
using a current of large quantity, we may succeed in gaining
metal and thus secure a deposit. This way of overcoming the
difficulty is assisted by using a very strong solution, which al-
lows a current of large quantity to pass with less resistance,
and also leaves less water uncombined to act on the metal.
By using these devices, Bunsen was enabled to obtain even
metallic calcium from a solution of its chloride.
By the density of the current we mean the number of am-
peres passing through each unit of surface of cathode or de-
positing surface. If the density is very great, it is necessary
that a brisk circulation be kept up in the solution to bring fresh
quantities of salt into the sphere of action and to remove the
impoverished solution ; otherwise, if a deficiency of salt occurs,
the solvent is attacked. Rapid circulation therefore favors
regular working.
In any electrolytic bath, the tension and density of the cur-
rent determine which of the several ingredients present will be
2,06 ALUMINIUM.
decomposed. Let us assume two compounds present, A and B,
of which ^ is a weaker compound than By either one of them
may be water, or they may both be anhydrous salts. In such
a liquid bath, a current just strong enough to decompose A
will not afifect B. When the current is just strong enough to
decompose B, the product will be the elements of A with a
trace of those of B/ but since the base in B is supposed to be a
stronger one than that in A, there will be a secondary action,
and the base of B will displace the base of A in the still unde-
composed compound, and B will be re-formed. This will be
the direct effect of increasing the tension of the current. How-
ever, if the density of the current is increased at the same time,
another principle comes into play. The base of B may be de-
posited so quickly that it has not time to react on A, and in
that case the deposit will contain the base of B. Also, if there
is a much larger proportion of B than of A present, a larger
proportion of its base will be deposited than before and escape
re-solution. Also, other things being equal, if the compound
B is more fluid or rather diffuses quicker in the bath than A,
more of it will get to the electrodes and a larger proportion be
decomposed.
We therefore see that when two or more compounds are
present, the relative amounts of each to be decomposed depend
1. Primarily, on the electro-motive force of the current,
which may be so regulated as to decompose them one after the "
other in the order of their electromotive force of decomposition.
2. On the density of the current at the electrodes. That is,
provided the tension of the current is sufficient to decompose
the stronger compound, the greater the density of the current
the greater the proportion of the stronger compound which
will be decomposed, other conditions being equal.
3. On the relative amounts of each present. Other condi-
tions being equal, the relative amount of a compound decom-
posed will increase as its proportion in the bath is increased.
4. On the relative rates of diffusion, or the rapidity with
which elements of the different compounds move towards the
electrodes.
REDUCTION OF ALUMINIUM COMPOUNDS. 307
The consideration of the electrolytic processes falls naturally
under two heads : —
I. Deposition from aqueous solution.
II. Non-aqueous electric processes.
I.
Deposition of Aluminium from Aqueovs Solution.
The status of this question is one of the curiosities of electro-
metallurgic science. Evidently attracted by the great reward
to be earned by success, many experimenters have labored in
this field, have recommended all sorts of processes, and pat-
ented all kinds of methods. We have inventors afiSrming in
the strongest manner the successful working of their methods,
while other experimenters have followed these recipes, and
tried almost every conceivable arrangement, yet report negative
results. To show that it is quite possible that many strong af-
firmations may be made in good faith, I have only to mention
the fact that in March, 1863, Mr. George Gore described in the
Philosophical Magazine some experiments by which he de-
posited coatings of aluminium from aqueous solutions, and
afterwards, in his text book of Electro-metallurgy, asserts that
he knows of no successful method of doing this thing. We
infer that Mr. Gore found that he was in error the first time.
So, if we take the position that aluminium cannot by any
methods so far advanced be deposited from aqueous solution
without using a soluble aluminium anode, we will have to ad-
mit that the proposers of many of the following processes are
probably misled by their enthusiasm in affirming so strongly
that they can do this thing. Yet the problem is not impossible
of solution.
Messrs. Thomas and Tilly* coat metals with aluminium and
its alloys by using a galvanic current and a solution of freshly
precipitated alumina dissolved in boihng water containing po-
tassium cyanide, or a solution of freshly calcined alum in
* English Patent, 1855, No. 2756.
308 ALUMINIUM.
aqueous potassium cyanide; also from several other liquids.
Their patent covers the deposition of the alloys of aluminium
with silver, tin, copper, iron, silver and copper, silver, and tin,
etc. etc., the positive electrode being of this metal or alloy.
M. Corbelli, of Florence,* deposits aluminium by electroylz-
ing a mixture of rock alum or sulphate of alumina (2 parts)
with calcium chloride or sodium chloride (i part) in aqueous
solution (7 parts), the anode being mercury placed at the
bottom of the solution and connected to the battery by an iron
wire coated with insulating material and dipping its uncovered
end into the mercury. The zinc cathode is immersed in the
solution. Aluminium is deposited on the zinc, as a blackish
powder or as a thin, compact sheet, and the chlorine which is
liberated at the anode unites with the mercury, forming calomel.
J. B. Thompsonf reports that he has for over two years been
depositing aluminium on iron, steel, and other metals, and
driving it into their surfaces at a heat of 500° F., and also de-
positing aluminium bronze of various tints, but declines to state
his process.
George Gore, Jthe noted electrician, recommended the fol-
lowing procedure for depositing aluminium on copper, brass, or
German silver: —
" Take equal measures of sulphuric acid and water, or one
part sulphuric acid, one part hydrochloric acid and two parts
of water, put into it half an ounce of pipe clay to the pint of
dilute acid, and boil for an hour. Take the clear, hot liquid
and immerse in it an earthen porous cell containing sulphuric
acid diluted with ten times its bulk of water, together with a
rod or plate of amalgamated zinc. Connect the zinc with the
positive wire of a Smee battery of three or four elements con-
nected for intensity. The article to be coated, well cleaned, is
connected with the negative pole and immersed in the hot clay
solution. In a few minutes a fine, white deposit of aluminium
* English Patent, 1858, No. 507.
fChem. News, xxiv. 194 (1871).
t Philosophical Magazine, March, 1863.
REDUCTION OF ALUMINIUM COMPOUNDS. 309
will appear all over its surface. It may then be taken out,
washed quickly in clean water, wiped dry, and polished. If a
thicker coating is required, it must be taken out as soon as the
deposit becomes dull, washed, dried, polished, and re-immersed,
and this must be repeated at intervals as often as it becomes
dull, until the required thickness is obtained. It is necessary
to have the acid well saturated by boiling, or no deposit will
be obtained."
Mierzinski asserts that Dr. Gore was mistaken when he sup-
posed this deposit to be aluminium, and in Gore's Text Book
of Electro-metallurgy no mention is made of these experi-
ments, the author thereby acknowledging the error. As to
what the deposit could have been, we are left to conjecture,
since no explanation has been advanced by Dr. Gore ; it may
possibly have been silicon, mercury, or zinc, as all three of
these were present besides aluminium.
J. A. Jeanfon* has patented a process for depositing alumin-
ium from an aqueous solution of a double salt of aluminium
and potassium of specific gravity 1.161 ; or from any solution
of an aluminium salt, such as sulphate, nitrate, cyanide, etc.,
concentrated to 20° B. at 50° F. He uses a battery of four
pairs of Smee's or three Bunsen's cells, with elements arranged
for intensity, and electrolyzes the solutions at 140° F. The
first solution will decompose without an aluminium anode, but
the others require such an anode on the negative pole. The
solution must be acidulated slightly with acid corresponding to
the salt used, the temperature being kept at 140° F. constantly.
More recently!, Jeangon has obtained a patent for the fol-
lowing process : " Subjecting a supersaturated acid solution of
a salt of aluminium to the action of a current passed from an
anode of aluminium in a state of division or porosity, pre-
senting a relatively large exposure of surface within a given
field of electric force, and a suitable metallic cathode." Further
* Annual Record of Science and Industry, 1875.
tU. S. Patent, 436,895; Sept. 23, i8go. (Specimens.)
3IO ALUMINIUM.
details state that the anode is to be prepared by melting alu-
minium iri a crucible and stirring in about 30 per cent, of car-
bon or a similar substance, and then moulding into shape. The
electrolyte is to be maintained at a high temperature, preferably
180° to 200° F., under which conditions a dense deposit is
obtained.
The writer has already stated that aluminium is being suc-
cessfully electro-plated from solution using aluminium anodes;
and, if the above process is the one which has been used in
Philadelphia by the Harvey Filley Plating Co., then I can cer-
tify to it having been successfully operated. The company
mentioned refuse to say anything about the process they use,
but I have been informed by outside parties that the above is
the one. It is certain, however, that very good specimens of
aluminium-plated ware have been made and sold by this firm,
several having been examined and tested by the writer person-
ally. A thin deposit on sheet-iron, which has been in my pos-
session over two years, shows no sign of rust or deterioration,
and suggests the practicability of thus making a substitute for
tin-plate of greater durability and which will not rust.
M. A. Bertrand * states that he deposited aluminium on a
plate of copper from a solution of double chloride of aluminium
and ammonia, by using a strong current, and the deposit was
capable of receiving a brilliant polish.
Jas. S. Haurd,t of Springfield, Mass., patented the elec-
trolysis of an aqueous solution formed by dissolving cryolite in
a solution of magnesium and manganous chlorides.
John Braun { decomposes a solution of alum, of specific
gravity 1.03 to 1.07, at the usual temperature, using an insolu-
ble anode. In the course of the operation, the sulphuric acid
set free is neutralized by the continual addition of alkali ; and,
afterwards, to avoid the precipitation of alumina, a non-volatile
organic acid, such as tartaric, is added to the solution. The
* Chem. News, xxiv. 227.
t U. S. Patent, 228,900, June 15, 1880.
X German Patent, No. 28,760 (1883'!.
REDUCTION OF ALUMINIUM COMPOUNDS. 3 II
intensity of the current is to be so regulated that for a bath of
lO to 20 Htres two Bunsen elements (about 20 centimetres
high) are used.
Dr. Fred. Fischer* stated that Braun's proposition was con-
trary to his experience. By passing a current of 8 to 9 volts
and 50 amperes, using from o.i to 10 amperes per sq. centi-
metre of cathode, with various neutral and basic aluminium
sulphate solutions, with and without organic acids, he obtained
no aluminium. He obtained a black deposit of copper sul-
phide on the copper anode, which had apparently been mis-
taken by Braun for aluminium.
Moses G. Farmer | has patented an apparatus for obtaining
aluminium electrically, consisting of a series of conducting cells
in the form of ladles, each ladle having a handle of conducting
material extending upwards above the bowl of the next suc-
ceeding ladle ; each ladle can be heated separately from the
rest ; the anodes are hung in the ladles, being suspended from
the handles of the preceding ladles, the ladles themselves being
the cathodes.
M. L. Senet X electrolyzes a saturated solution of aluminium
sulphate, separated by a porous septum from a solution of
sodium chloride. A current is used of 6 to 7 volts and 4
amperes. The double chloride, AlCl'.NaCl, is formed, then
decomposed, and the aluminium liberated deposited on the
negative electrode. It has later been remarked of this process
that it has not had the wished-for success on a large scale.
Col. Frismuth, of Philadelphia, purported to plate an alloy of
nickel and aluminium. He used an ammoniacal solution, prob-
ably of their sulphates. The plating certainly resembled
nickel, but that it contained aluminium the writer is not pre-
pared to assert.
Baron Overbeck and H. Neiwerth, of Hannover, § have
* Zeitschrift des Vereins Deutsche Ingenieurs, 1884, p. 557.
t U. S. Patent, No. 315,266, April, 1885.
t Cosmos les Mondes, Aug. 10, 1885.
§ English Pat., Dec. 15, 1883, No. 5756:
3 1 2 ALUMINIUM.
patented the following process : An aqueous or other solu-
tion of an organic salt of aluminium is used, or a mixture of
solutions which by double decomposition will yield such salt.
Or a mixture of a metallic chloride and aluminium sulphate
may be used, this yielding nascent aluminium chloride, which
the current splits up immediately into aluminium and chlorine.
Herman Reinbold* gives the following recipe, stating that it
furnishes excellent results : 50 parts of potash alum are dis-
solved in 300 parts of water, and to this are added 10 parts of
aluminium chloride. The whole is then heated to 200° F.,
cooled, and then 39 parts of potassium cyanide added. A
weak current should be used. It is stated that the plating,
when polished, will be found equal to the best silver plating.
" Iron," noticing this process, remarks, " there are a number of
formulae for electro-plating with aluminium, but few appear to
have attained to practical utility in the arts, for the reason that
there is no special demand for such processes. All the quali-
ties that are possessed by an electro-deposit of aluminium are
possessed to an equal or superior degree by other metals, silver,
nickel, platinum, etc. Furthermore, it obstinately refuses to
take and to retain a high lustre." This criticism is a little
overdrawn, since the one quality in which aluminium is super-
ior to silver — not blackening by contact with sulphurous vapor
— is not mentioned.
Under the name of Count R. de Montegelas, of Philadelphia,
several patents have been taken out in England for the elec-
trolysis of aqueous solutions, which may be summarized as
follows : —
f Alumina is treated with hydrochloric acid, and aluminium
chloride obtained in solution. The liquid is then placed in a
vessel into which dip a suitable anode and a cathode of brass or
copper. On passing an electric current through the bath the
iron present in the liquid is first deposited, and as soon as this
deposition ceases (as is apparent by the change of color of the
* Jeweler's Journal, September, 1887.
t English Patent, Aug. 18, 1886, No. 10607.
REDUCTION OF ALUMINIUM COMPOUNDS. 313
deposit) the liquid is decanted into another similar bath, and to
it is added about fifty per cent, by weight of the oxide of either
lead, tin or zinc. On sending a current through this bath,
aluminium together with the metal of the added oxide is said to
be deposited on the cathode.
* A rectangular vessel is divided into two unequal compart-
ments by a vertical porous partition, into the smaller of which
is placed a saturated solution of common salt, in which is im-
mersed a brass or copper electrode ; into the larger is put a so-
lution of aluminium chloride, immersed in which is an alumin-
ium electrode. On passing the current the latter solution,
which is normally yellow, is gradually decolorized and con-
verted into a solution of aluminium-sodium chloride. When
colorless, this solution is taken out and the aluminium deposited
in a similarly arranged vessel. The double chloride solution is
placed in the larger compartment, with an electrode of brass,
copper, or a thin plate of aluminium, while the smaller com-
partment contains a carbon electrode dipping into a solution of
salt and surrounded by fragments of a mixture of salt and
double chloride, fused together in equal parts.
The author has been given several ounces of a very fine me-
tallic powder said to have been made by these processes, and
which is certainly aluminium. As I am not satisfied, however,
that the specimen is really authentic, I feel justified in suspend-
ing a final expression of opinion on the process.
A Walker, of Tarnowitz, has patented the following methods
of procedure : j
a. Pure commercial hydrate is dissolved in nitric acid free
from chlorine, in slight excess, and tartaric acid added. The
Hquid is let clear for some time, any potassium bi-tartrate,
which may be formed from small quantities of potassium ad-
hering to the hydrate, filtered out, and the clear solution
electrolyzed. There is added to the solution during electrolysis
* English Patent, Feb. 3, 1887, No. 1751.
t German Pat. (D. R. P.) 40,626 (1887).
3 1 4 ALUMINIUM.
organic acid — as formic, acetic, citric, oxalic — or, better, ab-
solute alcohol.
b. A solution of aluminium nitrate, as far as possible free
from alkalies and sulphuric acid, is decomposed by a strong
dynamic current in baths arranged in series, using platinized
plates as anode and cathode. With a weak current of 0.02 to
0.05 amperes to a square centimetre, the aluminium separates
out on the cathode as a deep black deposit, sticking close to
the copper. The cathode is lifted from the solution, freed from
small quantities of alumina coating it by gentle rinsing, and
then the deposit washed off by a strong jet of water. The
powder obtained is washed further with clear, cold water, par-
ticularly free from sodium chloride, and dried by gentle heat-
ing in the air.
H. C. Bull* proposes to manufacture aluminium alloys by
using the metal to be alloyed with aluminium as a cathode in a
bath of aluminium sulphate, the anode being either of alumin-
ium or of an insoluble substance. When enough aluminium is
deposited, the cathode is taken out and melted down.
C. A. Burghardt and W. J. Twining, of Manchester, England,
have patented the following methods :
fTo a solution of sodium or potassium aluminate containing
about 7.2 oz. of aluminium per gallon are added 4 pounds of
95 per cent, potassium cyanide dissolved in a quart of water,
and then gradually 2j^ pounds of potassium bi-carbonate.
The whole is boiled 12 hours and made up to a gallon. The
bath is used at 175° F. with aluminium or platinum anode and
carbon or copper cathode. The addition of a little free hydro-
cyanic acid insures a bright deposit when articles are being
plated.
% Two and one-half kilos of aluminium sulphate in solution is
precipitated by ammonia, and then re-dissolved by adding \yi
kilos of caustic soda dissolved in a litre of water; the alumina
♦English Pat., 10,199 A. (1887).
t English Pat., July 2, 1887, No. 9389.
I German Pat. (D. R. P.), 45,020 (1887).
REDUCTION OF ALUMINIUM COMPOUNDS. 3x5
is thus slightly in excess. The hydrocyanic acid is added until
a slight precipitate appears. This solution, warmed to 80°, is
used as a bath from which aluminium is to be deposited.
*The bath is prepared by dissolving alumina in a solution of
chloride of copper, and treating further with caustic soda or
potash for the purpose of causing the aluminium and copper to
combine together. The precipitate, dissolved in hydrocyanic
acid and diluted, forms a bath of double cyanide, which when
electrolyzed deposits an alloy of aluminium and copper.
Besides the processes so far described, patents have been
taken out in England by Gerhard and Smith,f Taylor,| and
Coulson,§ the details of which have not been accessible to the
author.
Over against these statements of enthusiastic inventors, let
me place a few extracts from authorities who have given much
time and attention to the subject of electro-depositing alumin-
ium from solution without the use of an aluminium anode.
Sprague|| states his inability to deposit aluminium electric-
ally from solution.
Dr. Clemens Winckler IT states that he has spent much time
in trying all methods so far proposed, and comes to the conclu-
sion that aluminium cannot be deposited by electricity in the
wet way.
Dr. Geo. Gore** although having once proposed a method
which he said attained this end, yet in his later work on Elec-
tro-metallurgy does not mention his former proposition, and
quotes, apparently as coinciding with his own opinion, the
words of Sprague and Winckler given above.
* English Pat., Oct. 28, 1887, No. 2602.
tNo. 16,653 (1884).
J No. 1991 (1855).
§ No. 207s (1857).
II Sprague's Electricity, p. 309.
t Journal of the Chem. Soc, X. 1 134.
** Text-book of Electto- metallurgy.
3l6 ALUMINIUM.
Dr. S. Mierzinski* states, in 1883, that "the deposition of
aluminium from an aqueous solution of its salt has not yet been
accomplished."
Dr. W. Hampef claims to have shown that the electrolysis
of aqueous aluminous solutions, although frequently patented,
is not to be expected. From which we would infer that he
could not testify to it ever having been done.
Alexander Watt| holds that the electrolytic production of
aluminium ,from solution is very improbable. He tried acid
solutions, alkaline solutions, cyanide combinations, etc., under
most varied conditions, without any result.
Finally, I will quote from a letter of my good friend Dr.
Justin D. Lisle, of Springfield, O., who with ample means at
his disposal, an enthusiasm bred of love tor scientific truth, and
talent to guide him in his work, has reached the following re-
sults : " I have tried in almost every conceivable way to de-
posit it (aluminium) from aqueous solution by electricity,
using from i pint cells to 60 gallon cells successively ; the cells
were connected for quantity and for intensity; acid and neutral
solutions were used; carbon, platinum, and copper electrodes,
porous cups and diaphragms, were all thoroughly tried, without
the slightest deposit of metal. In some cases alumina was de-
posited, which has led me to think that aluminium was pri-
marily deposited, and owing to the fine state in which it existed
was promptly oxidized."
The following details of the operation of the electric plant of
the Tacony Metal Company, near Philadelphia, under the
supervision of Mr. J. D. Darling, are all that the writer has
been able to gather respecting their process. This company
had the contract to electroplate the exterior ironwork of the
tower of the Philadelphia Public Buildings, there being alto-
gether about 50,000 square feet to be plated, on which was to
be deposited 20,000 pounds of aluminium, or a little over six
* Die Fabrikation des Aluminiums.
tChem. Zeit. (Cothen), XI. 935.
I London Electrical Review, July, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 317
ounces to the foot. This would give a smooth coating j\ inch
thick. The cast-iron work is first given a coating of copper,
and the aluminium deposited on it, but it is stated that good
platings have been obtained directly on the cast-iron.
The largest pieces plated were columns 26 feet long and 3
feet in diameter. The whole operation of treating such a col-
umn lasted 1 1 days, while the plant could turn out one every
4 days. The operations were as follows :
(i) Boiling 24 hours in a strong solution of caustic soda,
after which well washed.
(2) Pickled in dilute sulphuric acid 24 hours, brushed vig-
orously and washed.
(3) Copper-plated by immersion 40 hours in a copper
cyanide(?) solution. The column was then brushed with par-
affine wax inside, any flaws soldered up, and —
(4) Copper-plated again in an ordinary copper-plating so-
lution for 72 hours, until 16 ounces of copper to the square
foot had been deposited.
(5 ) Put into the aluminium-plating tank, and 3 ounces of
aluminium per square foot deposited on it. Time, 72 hours.
Column then well washed in the sixth tank.
The dynamo used for operation 3 gives a current of 1000
amperes at 6 volts tension ; for operation 4, 4000 amperes
at 2.5 volts tension; for operation 5, 2000 amperes at 8 volts
tension. In the latter case, the current density at the depos-
iting surface was 8 amperes per square foot (86 amperes per
square metre). In this depositing tank, aluminium anodes 4
feet long, 12 inches wide and }( inch thick were used. Sixty
of these plates, weighing 35 pounds each, were hung around
the inside of the tank.
■ The company will give no information regarding the compo-
sition of the electrolyte. Concerning the conducting of thS
operation, Mr. Darling has stated that " Aluminium is more
difficult to deposit than any of the common metals, because of
its tendency to re-dissolve after being deposited. I find that
by using a solution of aluminium salt that has but a slight dis-
3l8 ALUMINIUM.
solving effect on aluminium, with a density of current of 8
amperes per square foot, and with sufficiently high voltage,
aluminium can be deposited at the rate of i gramme per hour
per square foot in a reguline state. With much higher cur-
rents it can be deposited quicker, but will be in a pulverulent
state, which does not adhere."
II.
Non-aqueous Electric Processes.
The above heading was originally written, "The electrolytic
decomposition of fused aluminium compounds," but I have
changed it to this form because it is doubtful, in several cases,
whether electrolytic decomposition really plays much of a role
in the isolation of the aluminium. In some processes a pow-
erful current is used and largely converted into heat, producing
temperatures never before used in industrial operations. In
such cases, chemical reactions, rendered possible by the very
high temperature, come into play and may even be the prin-
cipal means of reducing the aluminium compound. It has been
suggested that such processes should be classed apart as
"electro-thermal methods;" but such a division does not ap-
pear satisfactory to me, because in most cases we cannot say
positively that electrolysis does not play some part, and in
others it is simply impossible to decide which of the two agents
of reduction, electrolysis or chemical affinity, is the most active.
It has been suggested also that those processes in which high
voltage is used cannot be electrolytic, but must be electro-ther-
mal ; but such a division is not logical. If a bath is taking a
high voltage to work it, it may be solely from poor conductivity
in the electrolyte, and not because an arc is formed in the bath,
and true electrolysis may be going on to the full extent of the
power of the current. If we knew definitely, for each process,
which action played the principal part in the reduction, we
might classify the processes, but such a classification would not
be of much use. If it was absolutely necessary to make some
REDUCTION OF ALUMINIUM COMPOUNDS. 319
such division, I should consider as electro-thermal those pro-
cesses in which the parts of the apparatus used are not ar-
ranged as they should be to secure the maximum electrolytic
decomposition. We could thus, in such cases, say at once,
from a consideration of the apparatus and its manner of work-
ing, that electrolysis was evidently not contemplated in its con-
struction and could only play a minor part in its operation.
In conclusion, I regard it impossible to make an exact clas-
sification of these processes such as would be of any value to
the metallurgist or aid the general reader to a better under-
standing of them, and I therefore take them up in chronolog-
ical order.
Davy's Experiment (1810).
Sir Humphry Davy, in his Brompton Lecture before the
Royal Philosophical Society,* described the following attempt
to decompose alumina and obtain the metal of this earth. He
connected an iron wire with the negative pole of a battery con-
sisting of 1000 double plates. The wire was heated to white-
ness and then fused in contact with some moistened alumina,
the operation being performed in an atmosphere of hydrogen.
The iron became brittle, whiter, and on being dissolved in acid
gave a solution from which was precipitated alumina, identical
with that used.
It is evident that the alumina had been reduced by the
chemical action of the hydrogen gas, a reaction which we now
know takes place below the fusing point of alumina, 2200°, and
probably begins as low as 1700°.
Duvivier's Experiment (1854).
M. Duvivier f states that by passing an electric current from
eighty Bunsen cells through a small piece of laminated disthene
between two carbon points, the disthene melted entirely in two
or three minutes ; the elements which composed it were partly
* Philosophical Transactions, 1810.
fThe Chemist, Aug., 1854.
320 ALUMINIUM.
disunited by the power of the electric current, and some alu-
minium freed from its oxygen. Several globules of the metal
separated, one of which was as white and as hard as silver.
Since disthene is aluminium silicate, formula Al^Os.SiOj, it
is most likely that the metal obtained was highly siliceous
aluminium, since complete reduction of this compound would
give 54 parts of aluminium to 28 parts of silicon. The highly-
heated carbon particles of the electric arc were most probably
the reducing agent.
Bunsen's and Deville's Methods (1854).
A method of decomposing aluminium-sodium chloride by the
battery was discovered simultaneously by Deville in France and
Bunsen in Germany, in 1854, and is nothing else but an appli-
cation of the process already announced by Bunsen of decom-
posing magnesium chloride by the battery. Deville gives the
more minute account, and we therefore quote his description of
the process.
f " It appears to me impossible to obtain aluminium by the
battery in aqueous solutions. I should believe this to be an
absolute impossibility if the brilliant experiments of M. Bunsen
in the preparation of barium, chromium and manganese did not
shake my convictions. Still I must say that all the processes
of this description which have recently been published for the
preparation of aluminium have failed to give me any results.
Every one knows the elegant process by means of which M.
Bunsen has lately produced magnesium, decomposing fused mag-
nesium chloride by an electric current. The illustrious profes-
sor at Heidelberg has opened up a method which may lead to
very interesting results. However, the battery cannot be used
for decomposing aluminium chloride directly, which does not
melt, but volatilizes at a low temperature ; it is, therefore, neces-
sary to use some other material which is fusible and in which
*Tbe Chemist, Aug. 1854.
t Ann. de Chem. et de Phys. [3], 46, 452; Deville's " de rAluminium."
REDUCTION OF ALUMINIUM COMPOUNDS. 321
aluminium alone will be displaced by the current. I have found
this salt in the double chloride of aluminium and sodium, which
melts towards 185° C, is fixed at a somewhat high temperature,
although volatile below the fusing point of aluminium, and thus
unites all the desirable conditions.
" I put some of this double chloride into a porcelain crucible
separated imperfectly into two compartments by a thin leaf of
porcelain, and decomposed it by means of a battery of five ele-
ments and carbon electrodes. The crucible was heated more
and more as the operation progressed, for the contents became
less and less fusible, but the heat was not carried past the melt-
ing point of aluminium. Arrived at this point, after having
lifted out the diaphragm and electrodes, I heated the crucible
to bright redness, and found at the bottom a button of alumin-
ium, which was flattened out and shown to the Academy in the
S6ance of March 20, 1854. The button was accompanied by a
considerable quantity of carbon, which prevented the union of
a considerable mass of shot-metal. This carbon came from the
disintegration of the very dense gas-retort carbon electrodes; in
fact, the positive electrode was entirely eaten away in spite of
its considerable thickness. It was evident, then, that this appa-
ratus, although similar to that adopted by Bunsen for manufac-
turing magnesium, would not suit here, and the following is the
process which after many experiments I hold as best.
" To prepare the bath for decomposition, I heat a mixture of
2 parts aluminium chloride and i part sodium chloride, dry and
pulverized, to about 200° in a porcelain capsule. They com-
bine with disengagement of heat, and the resulting bath is very
fluid. The apparatus which I use for the decomposition com-
prises a glazed porcelain crucible, which as a precaution is
placed inside a larger one of clay. The whole is covered by a
porcelain cover pierced by a slit to give passage to a large thick
leaf of platinum, which serves as the negative electrode ; the lid
has also a hole through which is introduced, fitting closely, a
well-dried porous cylinder, the bottom of which is kept at some
distance from the inside of the porcelain crucible. This porous
322
ALUMINIUM.
vessel encloses a pencil of retort carbon, which serves as the
positive electrode. Melted double chloride is poured into the
porous jar and into the crucible so as to stand at the same
height in both vessels ; the whole is heated just enough to keep
the bath in fusion, and there is passed through it the current
from several Bunsen cells, two cells being strictly sufficient.
The annexed diagram shows the crucibles in section.
Fig. 28.
"The aluminium deposits with some sodium chloride on the
platinum leaf; the chlorine, with a little aluminium chloride, is
disengaged in the porous jar and forms white fumes, which are
prevented from rising by throwing into the jar from time to
time some dry, pulverized sodium chloride. To collect the
aluminium, the platinum leaf is removed when sufficiently
charged with the saline and metallic deposit; after letting it
cool, the deposit is rubbed off and the leaf placed in its former
position. The material thus detached, melted in a porcelain
crucible, and after cooling washed with water, yields a gray,
metallic powder, which by melting several times under a layer
of the double chloride is reunited into a button."
Bunsen* adopted a similar arrangement. The porcelain cru-
* Pogg. Annalen, 97, 648.
REDUCTION OF ALUMINIUM COMPOUNDS. 323
cible containing the bath of aluminium-sodium chloride kept in
fusion was divided into two compartments in its upper part by a
partition, in order to separate the chlorine liberated from the alu-
minium reduced. He made the two electrodes of retort carbon.
To reunite the pulverulent aluminium, Bunsen melted it in a bath
of the double chloride, continually throwing in enough sodium
chloride to keep the temperature of the bath about the fusing
point of silver.
As we have seen, Deville, without being acquainted with Bun-
sen's investigations, employed the same arrangement, but he
abandoned it because the retort carbon slowly disintegrated in
the bath, and a considerable quantity of double chloride was lost
by the higher heat necessary to reunite the globules of alumin-
ium after the electrolysis. Deville also observed that by working
at a higher temperature, as Bunsen had done, he obtained purer
metal, but in less quantity. The effect of the high heat is that
silicon chloride is formed and volatilizes, and the iron which
would have been reduced with the aluminium is transformed
into ferrous chloride by the aluminium chloride, and thus the
aluminium is purified of silicon and iron.
Plating aluminium on copper. — The same bath of double chlor-
ide of aluminium and sodium may be used for plating alumin-
ium in particular on copper, on which Capt. Caron experimented
with Deville. Deville says : " To succeed well, it is necessary to
use a bath of double chloride which has been entirely purified
from foreign metallic matter by the action of the battery itself.
When aluminium is being deposited at the negative pole, the first
portions of metal obtained are always brittle, the impurities in
the bath being removed in the first metal thrown down; so,
when the metal deposited appears pure, the piece of copper to
be plated is attached to this pole and a bar of pure aluminium
to the positive pole. However, a compact mixture of carbon
and alumina can be used instead of the aluminium anode, which
acts similarly to it and keeps the composition of the bath con-
stant. The temperature ought to be kept a little lower than the
fusing point of aluminium. The deposit takes place readily
324 ALUMINIUM.
and is very adherent, but it is difficult to prevent it being im-
pregnated with double chloride, which attacks it the moment
the piece is washed. The washing ought to be done in a large
quantity of water Cryolite might equally as well be used for
this operation, but its fiisibility should be increased by mixing
with it a little double chloride of aluminium and sodium and
some potassium chloride."
During a recent law-suit for infringement of the Hall process,
it was held by the defendants that Deville electrolyzed a fluoride
bath, (cryolite) in which alumina was present and therefore
would be dissolved. It appears quite evident, however, that
Deville did not use cryolite, because it would have destroyed
the porcelain crucibles and necessitated the use of special ap-
paratus which Deville does not even hint at. It is, moreover,
true that when alumina is mixed with carbon the latter prevents
the cryoHte from wetting or coming into actual contact with it.
In an experiment by the writer, a large cylinder of carbon into
which had been incorporated over 50 per cent, of alumina
was kept in molten cryolite for several hours, and on being
taken out showed not the slightest sign of corrosion. Judges
Taft and Ricks of Ohio very properly ruled that Deville's ex-
periments did not in any way disclose or operate on the princi-
ple utilized by Mr. Hall.
Le Chatellier's Method (1861).
The subject of this patent* was the decomposition of the
fused double chloride of aluminium and sodium, with the par-
ticular object of coating or plating other metals, the articles
being attached to the negative pole. About the only novelty
claimed in this patent was the use of a mixture of alumina and
carbon for the anode, but we see from the previous paragraph
that this was suggested by Deville several years before ; the
only real improvement was the placing of this anode inside a
porous cup, in order to prevent the disintegrated carbon from
* English Patent, 1861, No. 1214.
REDUCTION OF ALUMINIUM COMPOUNDS. 325
falling into the bath. This was really only the Deville process,
patented in England.
Monckton's Patent (1862).
Monckton* proposes to pass an electric current through a
reduction chamber, and in this way to raise the temperature
to such a point that alumina will be reduced by the carbon
present. We clearly see in this the germ of several more-
recently patented processes.
Gaudin's Process (1869).
Gaudin f reduces aluminium by a process to which he ap-
plies the somewhat doubtful title of economic. He melts to-
gether equal parts of cryolite and sodium chloride, and traverses
the fused mass by a galvanic current. Fluorine is evolved at
the positive pole, while aluminium accumulates at the negative.
The great difficulties in such a process are the obtaining of
suitable vessels to withstand the corrosion of the bath, the great
inconvenience of the escaping fluoride gas, and the increase of
resistance due to the change of composition of the bath. It
would need several additional patents to render this process
operative, without mentioning economy.
Kagensbusch' s Process (1872).
Kagensbusch,! of Leeds, proposes to melt clay with fluxes,
then adding zinc or a like metal to pass an electric current
through the fused mass, isolating an alloy of aluminium and
the metal, from which the foreign metal may be removed by
distillation, sublimation, or cupellation.
If the patentee had used pure alumina instead of clay, he
might have produced some aluminium by his process, but the
silicon in the clay would get into the zinc in larger proportion
* English Patent, 1862, No. 264.
t Moniteur Scientifique, xi., 62.
X English Patent, 1872, No. 481 1.
326 ALUMINIUM.
than the aluminium, rendering the succeeding operations for
obtaining pure aluminium impossible.
Berthaut's Proposition (1879).
Up to this time all the proposed electric processes were
confined to the use of a galvanic current, the cost of obtaining
which was a summary bar to all ideas of economical produc-
tion. About this period dynamo-electric machines were being
introduced into metallurgical practice, and Berthaut is the first
we can find who proposes their use in producing aluminium.
The process which he patented * is otherwise almost identical
with Le Chatellier's,
Grdtzel's Process (1883).
This process f has little claim to originality, except in the
details of the apparatus. A dynamo-electric current is used,
the electrolyte is fused cryolite or double chloride of aluminium
and sodium, and the anodes are of pressed carbon and alumina
— none of which points are new. However, the use of melting
pots of porcelain, alumina, or aluminium, and making them the
negative electrode, are points in which innovations are made.
In a furnace are put two to five pots, according to the power
of the dynamo used, each pot having a separate grate. The
pots are preferably of metal, cast-steel is used, and form the
negative electrodes. The positive electrode, K (Fig. 29), can
be made of a mixture of anhydrous alumina and carbon pressed
into shape and ignited. A mixture of alumina and gas-tar
answers very well ; or it can even be made of gas-tar and gas-
retort carbon. During the operation little pieces of carbon fall
from it and would contaminate the bath, but are kept from
doing so by the mantle G. This isolated vessel, G, is perforated
around the lower part at g, so that the molten electrolyte may
circulate through. The tube O' conducts reducing gas into the
* English Patent, 1879, No. 4087.
t German Patent (D. R. P.), No. 26962 (1883).
REDUCTION OF ALUMINIUM COMPOUNDS.
327
crucible, which leaves by the tube 0\ This reducing atmos-
phere is important, in order to protect from burning any metal
rising to the surface of the bath. The chlorine set free at the
electrode, K, partly combines with the alumina in it, regenera-
ting the bath, but some escapes, and, collecting in the upper
part of the surrounding mantle, G, is led away by a tube con-
FlG. 29.
necting with it. Instead of making the electrode K of carbon
and alumina, it may simply be of carbon, and then plates of
pressed alumina and carbon are placed in the bath close to the
electrode, K, but not connected with it. Also, in place of
making the crucible of metal and connecting it with the nega-
tive pole, it may be made of a non-conducting material, clay or
the like, and a metallic electrode — as, for instance, of alu-
minium— plunged into the bath.
In a later patent,* Gratzel states that the bath is decomposed
* English Patent; 14325, Nov. 23, 1885. U. S. Patent, 362441, May 3, 1887.
328 ALUMINIUM.
by a current of comparatively low tension if magnesium chloride
be present ; the chlorides of barium, strontium or calcium act
similarly.
Prof. F. Fischer* maintains as impracticable the use of plates
of pressed alumina and carbon, which can, further, only be
operative when they are made the positive electrode, and then
their electric resistance is too great. The incorporation into
them of copper filings, saturation with mercury, etc., give no
more practical results. There are also volatilized at the anodes
considerable quantities of aluminium chloride, varying in
amount with the strength of the current.
Large works were erected near Bremen by the Aluminium
und Magnesiumfabrik Pt. Gratzel, zu Hemelingen, in which
this process was installed. License was also granted to the
large chemical works of Schering, at Berlin, to operate it. R.
Biedermann, in commenting on the process in i886,f stated
that the results obtained so far were not fully satisfactory, but
the difficulties which had been met were of a kind which would
certainly be overcome. They were principally in the polariza-
tion of the cathode, by which a large part of the current was
neutralized. By using proper depolarizing substances this dif-
ficulty would be removed. The utilization of the chlorine
evolved would also very much decrease the expenses. A more
suitable slag, which collected the aluminium together better,
was also desirable. Finally, the metal produced was somewhat
impure, taking up iron from the iron pots and silicon from the
clay ones, to obviate which Biedermann recommended the use
of lime or magnesia vessels.
Prof. Fischer, as we have seen, maintained the uselessness of
Gratzel's patent claims, and his later expression of this opinion
in 1887 drew a reply from A. Saarburger, Jdirectorof the works
at Hemehngen, to the effect that since October, 1887, they had
* Wagner's Jahresbericht, 1884, p. 1319; 1887, p. 376.
fKerl und Stohman, 4th ed., p. 725.
{ Verein der Deutsche Ingenieure, Jan. 26, 1889.
REDUCTION OF ALUMINIUM COMPOUNDS. 329
abandoned the Gratzel process, and were making aluminium at
present by methods devised by Herr Saarburger; in conse-
quence of which fact the directors of the company decided in
January, 1888, to drop the addition Pt. Gratzel from the firm
name. The methods then in use at Hemelingen were kept secret,
but the author was informed by a friend in Hamburg that they
were using a modified Deville sodium process. Herr Saarbur-
ger informed me in October, 1888, that they were producing
pure aluminiuin at the rate of 12 tons a year, besides a large
quantity sold in alloys. An attractive pamphlet issued by this
firm set forth precautions to be used in making aluminium
alloys, together with a digest of their most important properties,
which we shall have occasion to quote from later in considering
those alloys.
The sharp decline in the price of aluminium in 1890 forced
this company out of the aluminium business.
Cowles Bros! Process.
Messrs. E. H. and A. H. Cowles patented in the United
States and Europe * an electric furnace and its application for
producing aluminium. Their patent claims " reducing an alu-
minium compound in company with a metal in presence of car-
bon in a furnace heated by electricity ; the alloy of aluminium
and the metal formed being further treated to separate out the
aluminium." The history of the development of this process
having already been sketched, we will proceed to describe the
details of its operation. The first public description was given
in two papers, one read before the American Association for the
Advancement of Science f by Prof. Chas. F. Mabery of the Case
School of Applied Science, Cleveland, the other before the
American Institute of Mining Engineers % by Dr. T. Sterry
Hunt, of Montreal.
* U. S. Patents 324658, 324659, Aug. 18, 1885; English Patent 9781, same date;
German Patent 33672.
t Ann Arbor Meeting, Aug. 28, 1885.
X Halifax Meeting, Sept. 16, 1885.
330 ALUMINIUM.
Prof. Mabery said in his paper : " Some time since, the Messrs.
Cowles conceived the idea of obtaining a continuous high tem-
perature on an extended scale by introducing into the path of
an electric current some material that would afford the requi-
site resistance, thereby producing a corresponding increase in
the temperature. After numerous experiments, coarsely pul-
verized carbon was selected as the best means for maintaining
an invariable resistance, and at the same time as the most
available substance for the reduction of oxides. When this
material, mixed with the oxide to be reduced, was made a part
of the electric circuit, inclosed in a fire-clay retort, and sub-
jected to the action of a current from a powerful dynamo, not
only was the oxide reduced, but the temperature increased to
such an extent that the whole interior of the retort fused com-
pletely. In other experiments lumps of lime, sand, and corun-
dum were fused, with a reduction of the corresponding metal ;
on cooling, the lime formed large, well-defined crystals, the
corundum beautiful red-green and blue octahedral crystals.
Following up these results, it was soon found that the intense
heat thus produced could be utilized for the reduction of oxides
in large quantities, and experiments were next tried on a large
scale with the current from a fifty horse-power dyamo. For
the protection of the walls of the furnace, which were of fire-
brick, a mixture of ore and coarsely pulverized gas-carbon was
made a central core, and was surrounded on the side and bot-
tom by fine charcoal, the current following the lesser resistance
of the core from carbon electrodes inserted in the ends of the
furnace in contact with the core. The furnace was charged by
first filling it with charcoal, making a trough in the centre, and
filling this with the ore mixture, the whole being covered with
a layer of coarse charcoal. The furnace was closed on top
with fire-brick slabs containing tivo or three holes for the
escape of the gaseous products of the reduction, and the whole
furnace was made air-tight by luting with fire-clay. Within a
few minutes after starting the dynamo, a stream of carbonic
oxide issued through the openings, burning usually with a flame
REDUCTION OF ALUMINIUM COMPOUNDS. 33 1
eighteen inches high. The time required for complete reduc-
tion was ordinarily about an hour. Experience has already
shown that aluminium, silicon, boron, manganese, sodium and
potassium can be reduced from their oxides with ease. In fact,
there is no oxide that can withstand the temperature attainable
in this furnace. Charcoal is changed to graphite; does this
indicate fusion? As to what can be accomplished by convert-
ing enormous electrical energy into heat within narrow limits,
it can only be said that it opens the way into an extensive field
of pure and applied chemistry. It is not difficult to conceive
of temperature limited only by the power of carbon to resist
fusion.
" Since the motive power is the chief expense in accomplish-
ing reductions by this method, its commercial success is
closely connected with obtaining power cheaply. Realizing
the importance of this point, Messrs. Cowles have purchased at
Lockport, N. Y., a water-power where they can utilize I200
horse-power. An important feature in the use of these furnaces
from a commercial standpoint is the slight technical skill re-
quired in their manipulation. The four furnaces operated in
the experimental laboratory at Cleveland are in charge of two
young men, who six months ago knew absolutely nothing
of electricity. The products at present manufactured are
the various grades of aluminium bronze, made from a rich
furnace product obtained by adding copper to the charge of
ore. Aluminium silver is also made ; and a boron bronze may
be prepared by the reduction of boracic acid in contact with
copper, while silicon bronze is made by reducing silica in con-
tact with copper. As commercial results may be mentioned
the production in the experimental laboratory, which averages
50 lbs. of 10 per cent, aluminium bronze daily, which can be
supplied to the trade in large quantities on the basis of $5 per
lb. for the aluminium contained, the lowest market quotation of
aluminium being now $15 per lb."
Dr. Hunt stated further that if the mixture consisted of alu-
mina and carbon only, the reduced metal volatilized, part es-
332 ALUMINIUM.
caping into the air and burning to alumina, part condensing in
the upper layer of charcoal, affording thus crystalline masses of
nearly pure aluminium and yellow crystals supposed to be a
compound of aluminium with carbon. Great loss was met in
collecting this divided metal into an ingot, so that only small
quantities were really obtained. To gather all the aluminium
together, a metal such as copper was added, thus producing an
alloy with 15 to 20 per cent, of aluminium ; on substituting
this alloy for pure copper in another operation, an alloy with
over 30 per cent, of aluminium was obtained.
Dr. Hunt, in a later paper,* stated that pure aluminium has
been obtained in this process by first producing in the furnace
an alloy of aluminium and tin, then melting this with lead,
when the latter takes up the tin and sinks with it beneath
the aluminium. He also stated that in the early experiments a
dynamo driven by a 30 horse-power engine yielded a daily out-
put of 50 lbs. of 10 per cent, aluminium bronze, but with a
larger machine the output was proportionally much greater.
In the latest practice, one-half cent per horse-power per hour
is said to cover the expense of working, making the 10 per
cent, bronze cost about 5 cents per lb. over the copper used.
Various shapes of furnaces have been used by the Cowles
Bros., the first described being a rectangular box, lined with
carbon, with the electrodes passing through the ends. Al-
though two other forms have been patented, we understand
that the kind now used, aad which is described at length in Mr.
Thompson's paper, is also of the oblong, horizontal style.
Chas. S. Bradley and Francis B. Crocker, of New York, patented
and assigned to the Cowles Electric Smelting Company,f the
use of a retort, composed of conducting material, surrounded
by a substance which is a poor conductor of heat, and having
inside a mixture of charcoal and the ore to be heated. Electric
connection being made with the ends of the retort, the walls of
♦National Academy of Science, Washington Meeting, April 30, 1886.
tU. S. Patent 335499, Feb. j., 1886.
REDUCTION OF ALUMINIUM COMPOUNDS. 333
the retort and the material in it are included in the circuit and
constitute the greater part of the resistance. The retort may
be stoppered at each end during the operation, and the heating
thus performed in a reducing atmosphere. Mr. A. H. Cowles
devised a style of furnace adapted for continuous working and
utilizing the full current of a dynamo of the largest size.f The
electrodes are tube-shaped and placed vertically. The positive
pole is above, and is surmounted by a funnel in which the
mixture for reduction is placed. The regular delivery of the
mixture is facilitated by a carbon rod, passing through the
cover of the funnel, which is serrated on the end and can be
worked up and down. The melted alloy produced, with any
slag, passes down through the negative electrode. The dis-
tance between the poles can be regulated by moving the upper
one, and the whole is inclosed in a fire-brick chamber. The
space between the electrodes and the walls is filled with an iso-
lating material, which is compact around the lower electrode
but coarse grained around the upper to facilitate the escape of
the gases produced. The chamber is tightly closed excepting
a small tube for the escape of gas.
A very complete description of the Cowles process was given
by Mr, W. P. Thompson (agent for the Cowles Co. in England)
in a paper read before the Liverpool Section of the Society of
Chemical Industry. f He describes the process as then carried
on in Lockport, the dynamo used being a large Brush machine
weighing 2J^ tons and consuming about lOO horse-power in
being driven at 900 revolutions per minute.
" Conduction of the current of the large dynamo to the furnace
and back is accompHshed by a complete metallic circuit, except
where it is broken by the interposition of the carbon electrodes
and the mass of pulverized carbon in which the reduction takes
place. The circuit is of 13 copper wires, each 0.3 inch in dia-
meter. There is likewise in the circuit an ampere meter, or am-
* English Patent 4664 (1887).
.f Journal of the Society of Chemical Industry, April 29, 1886.
334
ALUMINIUM.
meter, through whose helix the whole current flows, indicating
the total strength of the current being used. This is an import-
ant element in the management of the furnace, for, by the posi-
tion of the finger on the dial, the furnace attendant can tell to a
nicety what is being done by the current in the furnace. Be-
tween the ammeter and the furnace is a resistance coil of Ger-
man silver kept in water, throwing more or less resistance into
the circuit as desired. This is a safety appliance used in
changing the current from one furnace to another, or to choke
off the current before breaking it by a switch.
"The furnace (see Figs. 30, 31, 32) is simply a rectangular
Fig. 30.
box. A, one foot wide, five feet long inside, and fifteen inches
deep, made of fire-brick. From the opposite ends through the
pipes BB the two electrodes CC pass. The electrodes are im-
mense electric-light carbons three inches in diameter and thirty
Fig. 31.
LONGITUDINAL SECTION.
inches long. If larger electrodes are required, a series this size
must be used instead, as so far all attempts to make larger car-
bons that will not disintegrate on becoming incandescent have
failed. The ends of the carbons are placed within a few inches
REDUCTION OF ALUMINIUM COMPOUNDS.
335
of each other in the middle of the furnace, and the resistance
coil and ammeter are placed in the circuit. The ammeter regis-
ters 50 to 2000 amperes. These connections made, the furnace
is ready for charging.
" The walls of the furnace must first be protected, or the in-
tense heat would melt the fire-brick. The question arose, what
would be the best substance to line the walls. Finely powdered
charcoal is a poor conductor of electricity, is considered infusi-
ble and the best non-conductor of heat of all solids. From
these properties it would seem the best material. As long as
Fig. 32.
TRANSVERSE SECTION.
air is excluded it will not burn. But it is found that after using
pure charcoal a few times it becomes valueless ; it retains its
woody structure, as is shown in larger pieces, but is changed
to graphite, a good conductor of electricity, and thereby tends
to diffuse the current through the lining, heating it and the walls.
The fine charcoal is therefore washed in a solution of Hme-
water, and after drying each particle is insulated by a fine
coating of lime. The bottom of the furnace is now filled with
this lining about two or three inches deep. A sheet-iron gauge
is then placed along the sides of the electrodes, leaving about
two inches between them and the side walls, in which space
more of the charcoal is placed. The charge E, consisting of
about 25 pounds of alumina, iii its native form as corundum, 12
336 ALUMINIUM.
pounds of charcoal and carbon, and 50 pounds of granulated
copper, is now placed within the gauge and spread around the
electrodes to within a foot of each end of the furnace. For
making iron alloy where silicon also is not harmful, bauxite or
various clays containing iron and silica may be used instead of
the pure alumina or corundum. In place of granulated cop-
per, a series of short copper wires or bars can be placed parallel
to each other and transverse to the furnace, among the alumina
and carbon, it being found that where grains are used they
sometimes fuse together in such a way as to short-circuit the
current. After this, a bed of charcoal, F, the granules of which
vary in size from a chestnut to a hickory, is spread over all,
and the gauge drawn out. This coarse bed of charcoal above
the charge allows free escape of the carbonic oxide generated in
the reduction. The charge being in place, an iron top, G,
lined with fire-brick, is placed over the whole furnace and the
crevices luted to prevent access of air. The brick of the walls
insulate the cover from the current.
" Now that the furnace is charged, and the cover luted down,
it is started. The ends of the electrodes were in the beginning
placed close together, as shown in the longitudinal section, and
for this cause the internal resistance of the furnace may be too
low for the dynamo, and cause a short circuit. The operator,
therefore, puts sufficient resistance into the circuit, and by
watching the ammeter, and now and then moving one of the
electrodes out a trifle, he can prevent undue short-circuiting in
the beginning of the operation. In about ten minutes, the cop-
per between the electrodes has been melted and the latter are
moved far enough apart so that the current becomes steady.
The current is now increased till 1300 amperes are going
through, driven by 50 volts. Carbonic oxide has already com-
menced to escape through the two orifices in the top, where it
burns with a white flame. By slight movements outward of the
electrodes during the coming five hours, the internal resistance
in the furnace is kept constant, and at the same time all the
different parts of the charge are brought in turn into the zone
REDUCTION OF ALUMINIUM COMPOUNDS. 337
of reduction. At the close of the run the electrodes are in the
position shown in the plan, the furnace is shut down by placing
a resistance in the circuit, and then the current is switched into
another furnace charged in a similar manner. It is found that
the product is larger if the carbons are inclined at angles of 30°
to the horizontal plane, as in Fig. 33.
Fig. 33-
SECTION OF THE COWLES FURNACE.
" This regulating of the furnace by hand is rather costly and
unsatisfactory. Several experiments have therefore been tried
to make it self-regulating, and on January 26, 1886, a British
patent was applied for by Cowles Bros, covering an arrange-
ment for operating the electrodes by means of a shunt circuit,
electro-magnet, and vibrating armature. Moreover, if the elec-
trodes were drawn back and exposed to the air in their highly
heated state, they would be rapidly wasted away. To obviate
this, Messrs. Cowles placed what may be called a stufifiing-box
around them, consisting of a copper box filled with copper shot.
The wires are attached to the boxes instead of the electrodes.
The hot electrodes as they emerge from the furnace first en-
counter the shot, which rapidly carry off the heat, and by the
time they emerge from the box they are too cool to be oxidized
by contact with the air.
" Ninety horse-power have been pumped into the furnace for
five hours. At the beginning of the operation the copper first
melted in the centre of the furnace. There was no escape for
the heat continually generated, and the temperature increased
until the refractory corundum melted, and being surrounded on
all sides by carbon, gave up its oxygen. This oxygen, uniting
with the carbon to form carbonic oxide, has generated heat
338 ALUMINIUM.
which certainly aids in the process. The copper has had noth-
ing to do with the reaction, as it will take place in its absence.
Whether the reaction is due to the intense heat or to electric
action it is difficult to say. If it be electric, it is Messrs. Cowles'
impression that we have here a case where electrolysis can be
accomplished by an alternating current, although it has not
been tried as yet. Were the copper absent, the aluminium set
free would now absorb carbon, and become a yellow crystal-
line carbide of aluminium ; but, instead of that, the copper has
become a boiling, seething mass, and the bubblings of its vapors
may distinctly be heard. The vapors probably rise an inch or
two, condense, and fall back, carrying with them the freed alu-
minium. This continues until the current is taken ofif the fur-
nace, when we have the copper charged with 1 5 to 30 per cent.,
and in some cases as high as 40 per cent, of its weight of alu-
minium, and a little silicon. After cooling the furnace this
rich alloy is removed. A valuable property of the fine charcoal
is that the metal does not spread and run through the inter-
stices, but remains as a liquid mass, surrounded below and on
the sides by fine charcoal, which sustains it just as flour or
other fine dust will sustain drops of water for considerable
periods, without allowing them to sink in. The alloy is white
and brittle. This metal is then melted in an ordinary crucible
furnace, poured into large ingots, the amount of aluminium in
it determined by analysis, again melted, and the requisite
amount of copper added to make the bronze desired.
"Two runs produce in ten hours' average work 100 pounds
of white metal, from which it is estimated that Cowles Bros., at
Lockport are producing aluminium in its alloys at a cost of
about 40 cents per lb. The Cowles Company will shortly have
1200 horse-power furnaces. With a larger furnace there is no
reason why it should not be made to run continuously, like the
ordinary blast furnace.
" In place of the copper any non-volatile metal may be used
as a condenser to unite with any metal it may be desired to
reduce, provided, of course, that the two metals are of such a
REDUCTION OF ALUMINIUM COMPOUNDS. 339
nature that they will unite at this high temperature. In this
way aluminium may be alloyed with iron, nickel, silver, tin or
cobalt. Messrs. Cowles have made alloys containing 50 alu-
minium to 50 of iron, 30 aluminium to 70 of copper, and 25
aluminium to 75 of nickel. Silicon or boron or other rare
metals may be combined in the same way, or tertiary alloys
may be produced ; as, for instance, where fire- clay is reduced
in presence of copper we obtain an alloy of aluminium, silicon
and copper."
Soon after Mr. Thompson's description, the plant at Lock-
port was increased by the addition of the largest dynamo up to
that time constructed, built by the Brush Electric Company,
and dubbed the " Colossus." This machine weighs almost ten
tons, and when driven at 423 revolutions per minute it pro-
duced a useful current of 3400 amperes at a tension of 68 volts,
or at 405 revolutions produced a current of 3200 amperes with
83 volts electro-motive force, indicating 249,000 Watts or 334
electric horse-power. The steam engine was, in the latter case,
developing nearly 400 horse-power, and could not supply
more ; it was judged that the dynamo could have been driven
to 300,000 Watts with safety. The first run with this machine
was made in September, 1886. The furnaces used for this cur-
rent are of the same style as that described by Mr. Thompson,
but are larger, the charge being 60 lbs. of corundum, 60 lbs. of
granulated copper, 30 lbs. of coarse charcoal besides the pulver-
ized lime-coated charcoal used in packing. The operation of
reducing this charge takes about two hours. As soon as the
operation is finished the current is switched off into another
furnace prepared and charged, so that the dynamo is kept work-
ing continuously. In 1888, the Cowles Company had two of
these large dynamos in operation, and eight furnaces in use.
With two-hour runs a furnace is tapped every hour, producing
about 80 lbs. of bronze averaging 18 per cent, of aluminium.
The capacity of the plant is, therefore, about i}i tons of 10
per cent, bronze per day. Their alloys were sold in 1890 on
the basis of $2.50 per lb. for the contained aluminium.
340
ALUMINIUM.
The Cowles Syndicate Company, of England, located at
Stoke-on-Trent, have set up a large plant at Milton, where, pro-
fiting by the experience of the parent concern in America, still
larger electric currents are used, these being found more eco-
nomical. The dynamo in use at this works was built by Cromp-
ton, and supplies a current of 5000-6000 amperes at 50 to 60
volts. There are two furnace-rooms, each containing six fur-
naces, aluminium and silicon bronze being produced in one
room, and ferro-aluminium in the other. The furnaces used
measure 60 by 20 by 36 inches, inside dimensions, and differ
from those previously shown by having the electrodes inclined
at an angle of about 30°. (See Figs. 33, 34). The electrodes
COWLES' ELECTRIC SMELTING FURNACES AT STOKE-ON-TRENT, ENGLAND.
used are formed by bundling together 9 carbon rods, each 2^^
inches in diameter, each electrode weighing 20 lbs. More re-
cently larger carbons have been obtained, 3 inches in diameter,
and an electrode formed of five of these weighs 36 lbs. The
furnace is charge^ as previously described.
The current is started at 3000 amperes, gradually increasing
to 5000 during the first half hour, and then keeping steady
until the run is ended, which is about one and a half hours
from starting. The product of each run is about 100 lbs. of
raw bronze containing 15 to 20 per cent, of aluminium. The
return is said to average i lb. of contained aluminium per 18
REDUCTION OF ALUMINIUM COMPOUNDS, 34I
electric horse-power hours, or ij^ lbs. per electric horse-
power per day. The works produce about 200 lbs. of alumin-
ium contained in alloys per day. The raw bronze is stacked
until several runs have accumulated, then a large batch is melted
at once in a reverberatory furnace, refined and diluted to the
proportion of aluminium required by adding pure copper.
The Cowles Company, both in England and America, pro-
duce six standard grades of bronze as follows :
'Special" A.
A
B
C
D
E
11
per
cent, of aluminium
10
( it
TA
it It
S-SV2
t ti
t it
i ti
Their ferro-aluminium is sold with usually 5 to 7 per cent.
of aluminium, but 10, 13, and 15 per cent, is furnished if
asked for.
Products of the Cowles furnace. — Dr. W.. Hampe obtained the
following results on analyzing a sample of Cowles Bros.' 10 per
cent, bronze :
Copper 90.058
Aluminium 8.236
Silicon 1.596
Carbon. 0.104
Magnesium 0.019
Iron trace.
100.013
A sample of 10 per cent, bronze, made in the early part of
1886, and analyzed in the laboratory of the Stevens Institute,
showed —
Copper 88.0
Aluminium 6.3
Silicon 6.5
but it is evident that the percentage of silicon has since then
been lowered.
342 ALUMINIUM.
The ferro-aluminium used by Mr. Keep in his tests on cast-
iron was furnished by the Cowles Company, and analyzed —
Aluminium I ^4^
Silicon , 3'86
A sample shipped to England in December, 1886, contained —
Iron 86.69
Combined carbon I.oi
Graphitic carbon 1.9'
Total 2.92
Silicon 2.40
Manganese 0.31
Aluminium 6.50
Copper 1.05
Sulphur 0.00
Phosphorus 0.13
85.46
86.04
86.00
84.00
8.65
9.00
9.25
10.50
2.20
2.52
2.3s
2.40
3-77
2.41
2.50
The copper in this alloy was present by accident, the alloy
regularly made containing none, but the rest of the analysis
gives a correct idea of the constitution of the alloy. Prof.
Mabery gives several analyses of Cowles' ferro-aluminium : — *
Iron 85.17
Aluminium 8.02
Silicon 2.36
Carbon
The slags formed in the furnace in producing this alloy were
analyzed as follows : —
Silica 0.78 4.10
Alumina (insoluble) 0.20 —
Lime 28.50 14.00
Iron 1.50 29.16
Alumina (soluble) -(- aluminium 38.00 48.70
Sulphur 0.50 —
Graphite 5.00 2.60
Combined carbon 0.90 0.48
The slags formed when producing bronze vary in composition,
"American Chemical Journal, 1887, p. 11.
REDUCTION OF ALUMINIUM COMPOUNDS. 343
and are usually crystalline, with a shining, vitreous lustre.
Their analysis shows —
Alumina (insoluble) 55.30 66.84 —
Alumina (soluble) + aluminium 21.80 14.20 —
Lime 3.70 1.44 6.77
Copper — 3.32 i.oo
Carbon 0.65
The lime present probably existed as calcium aluminate. These
slags contained only a small amount of aluminium, rarely any
iron, and were usually free from silica.
The same chemist analyzed a peculiar product sometimes
formed in the furnace when smelting for bronze, in the shape
of crystalline masses, steel-gray to bright yellow in color, semi-
transparent and with a resinous lustre. These all contained
aluminium, copper, silicon and calcium in various proportions,
and when exposed to the air fell to powder. Analyses gave
Copper 26.70 35-0° 20.00 —
Aluminium 66.20 53-30 74.32 15.23
Silicon 5.00 12.30 2.86 20.55
Calcium 2.00 0.20 2.86 ^
Tin _ _ _ 49.26
99.90 100.80 100.04 85.04
The latter product was formed in smelting for aluminium-tin.
Prof. Mabery also found that the soot collecting at the ori-
fices on top of the furnace contained 10 to 12 per cent, of alu-
minium ; also that when alumina and carbon alone were heated
and silica was present, the aluminium formed dissolved up to
10 per cent, of silicon, which, on dissolving the aluminium in
hydrochloric acid, was left as crystalline or graphitic silicon.
Reactions in Cowles' process. — The inventors, themselves,
claim " reduction in a furnace heated by electricity in presence
of carbon and a metal." In their first pamphlet they say that
" the Cowles process accomplishes the reduction of alumina by
carbon and heat." Professor Mabery and Dr. Hunt, already
344 ALUMINIUM.
quoted, and Dr. Kosman * look at the process in no other light
than that the electric current is utilized simply by its conver-
sion into heat by the resistance offered, and that pure elec-
trolysis is either absent or occurs to so small an extent as to be
inappreciable. Indeed, if we consider the arrangement of the
parts in the Cowles furnace we see every effort made to oppose
a uniform, high resistance to the passage of the current and so
convert its energy into heat, and an entire absence of any of
the usual arrangements for electrolysis. For instance, elec-
trolysis requires a fluid bath in circulation, so that each ele-
ment of the electrolyte may be continuously liberated at one of
the poles and the presence of any foreign material, as bits of
carbon, between the poles is to be avoided if possible, since
they short-circuit the current and hinder electrolysis proper.
I think the arrangement of the furnace shows no attempt to
fulfil any of the usual conditions for electrolysis, but is one of
the best arrangements for converting the energy of the current
entirely into heat. Dr. Hampe, however, in spite of these
evident facts, draws the conclusion that because he was unable
to reduce alumina by carbon in presence of copper at the tem-
perature of a Deville lime-furnace, that it was therefore to be
assumed that even the somewhat higher temperature of the
electric furnace alone would be insufficient to accomplish the
desired reaction, and hence the effect of the electric arc must
be not only electro-thermic in supplying heat, but afterwards
electrolytic, in decomposing the fused alumina.
If we figure out the useful effect of the current, i. e., the pro-
portion of its energy utilized for the purpose of reducing alumina,
we find a low figure ; but it is well to note that although the
power required is one of the main features of this way of reduction,
yet this item is so cheap at the firm's works that it becomes a
secondary consideration in the economy of the process. A 300
horse-power current is equivalent to an expenditure of
300 7 — ?__ jg J 000 calories of heat per hour. Theoretically,
424
* Stahl und Eisen, Jan. I
REDUCTION OF ALUMINIUM COMPOUNDS. 345
this amount of heat would produce i^i^ = 261^ kilos or 58
pounds of aluminium. However, about 7 pounds are obtained
in an hour's working, which would show a useful effect of 12
per cent. This should even be diminished, since no account
has been taken of the combustion of carbon in the furnace to
carbonic oxide. The remainder of the heat account, probably
90 per cent, of the whole, is partly accounted for by the heat
contained in the gases escaping and the materials withdrawn
from the furnace (of which no resonable estimate can be made,
since the question of temperatures is so uncertain) and the
large remainder must be put down as lost by radiation and
conduction. As before remarked, water power is obtained by
this company very cheaply, and even this large loss does not
make much show in the cost of the alloy, yet the figures show
that a much larger useful effect should be possible, and it is not
at all improbable that the prospect of getting double or triple
the present output from the same plant is at present inciting
the managers to fresh exertions in utilizing the power to better
advantage.
Mr. H. T. Dagger's paper* on the Cowles process in Eng-
land, states that the product at their Milton works is i lb. of
aluminium to 18 electric horse-power per hour, which would
show that the dissociation of the alumina represented nearly 30
per cent, of the energy of the current ; but the data given in the
body of this gentleman's paper (p. 303 ) do not seem to indi-
cate so large a return as is stated above. Mr. Dagger, more-
over, maintains the purely electro-thermic action of the current,
denying that any electrolysis takes place at all, citing an ex-
periment with the alternating current in one of these furnaces,
which produced as much aluminium per horse-power as did the
direct current. In such an experiment electrolysis must neces-
sarily be absent.
In the discussion of Heroult's alloy process it will be shown
that in both it and Cowles' process the largest part of the re-
* British Association for Advancement of Science, Newcastle, 1889.
346 ALUMINIUM.
duction must necessarily be performed by chemical and not by
electrolytic action. I do not introduce this discussion here,
since the two processes resemble each other so closely in the
reaction involved that they can best be considered together.
Since 1892 no aluminium has been made in England by this
process, as the low price of pure aluminium killed the market
for ready-made aluminium alloys. I cannot say exactly to
what extent the Lockport works is running at the present time,
but it is probable that the death of one of the Cowles brothers
in 1893 and the sharp competition from pure aluminium have
seriously hampered the business of the American company.
At least, their products are not frequently seen on the market.
It may be proper to interject here mention of an unfortunate
occurrence in the history of the Cowles Company. They sold
only aluminium alloys until January, 1891, when they began
to advertise and sell pure aluminium made, it was said, by a
new process. The Pittsburgh Reduction Company working
the Hall process were then selling pure aluminium as low as
$1.50 per pound, while the Cowles Company commenced sell-
ing as cheap as $1.00. Inside of two months the Pittsburgh
Reduction Company instituted suit for infringement of the
Hall patents, asking the courts meanwhile for a preliminary
injunction. Judge Ricks, of Ohio, denied a complete injunc-
tion, but restrained the defendants from increasing the output
of their plant during the trial of the suit, or from selling alu-
minium below a price to be named by the complainants. The
latter named $1.50 per pound, and this fixed the market price
for some months. Several metallurgical experts of wide repu-
tation were engaged by both sides, and very voluminous testi-
mony was taken. While the suit was pending, the price of
aluminium was reduced by the European makers to 5 marks a
kilo (56 cents a pound), at which price important quantities
began to be imported, and the domestic makers could sell very
Httle at $1.50. In consequence, the Pittsburgh Reduction
Company notified the court that it would sell as low as $0.50
per pound. At this price, which was very nearly the cost of
REDUCTION OF ALUMINIUM COMPOUNDS. 347
production, aluminium continued until the suit was finally de-
cided, in February, 1893, in favor of the Hall process. Judges
Taft and Ricks decided that the Cowles Company were using
the Hall process when they electrolyzed a bath of molten
cryolite in which alumina was dissolved, and they were ordered
to stop the infringement and to pay the damages which it
might be estimated that their infringement had caused the
complainants' business.
Menges' Patent.
* This inventor proposes to produce aluminium or aluminium
bronze by mixing aluminous material with suitable conducting
material, such as coal, and a cohesive material, then pressing
into cylinders and baking hard. These strong, compact bars
conduct electricity, and are to be used like the carbon elec-
trodes of electric lamps in a suitably inclosed space.
Farmer's Patent.
M. G. Farmer f mixes aluminous material with molasses or
pitch, making a paste which is moulded into sticks, burned,
and used as electrodes, inclosed in a furnace. Aluminium is
produced by the arc, and drops into a crucible placed imme-
diately beneath.
Several other persons have patented exactly the same
method of procedure as that indicated by Menges and Farmer,
with the modification in some cases of mixing iron or copper
turnings with the aluminous material, and having the melted
material drop into a furnace kept hot by burning ordinary fuel.
Such a method of reducing refractory ores was even suggested
as far back as 1853. None of such processes are likely to give
results sufficiently economical for commercial use.
Kleiner's Process (1886).
This was devised by Dr. Ed. Kleiner of Zurich, Switzerland,
* German Patent, 40354 (1887).
t English Patent, 10815, Aug. 6, 1887.
348 ALUMINIUM.
and was patented in most of the European States. The Eng-
lish patent is dated 1886.* The first attempts to operate it
were at the Rhine Falls, Schaffhausen, and were promising
enough to induce Messrs. J. G. Nethers, Sons & Co., pro-
prietors of an iron works there, to try to obtain water rights for
1500 horse power, announcing that a company (the Kleiner
Gesellschaft) with a capital of 12,000,000 francs, was prepared
to undertake the enterprise and build large works. The pro-
position is said to have met with strong opposition from the
hotel-keepers and those interested in the falls as an attraction
for tourists, and the government declined the grant, consider-
ing that the picturesqueness of the falls would be seriously
afifected. This is the reason given by those interested in the
process for its not being carried out in Switzerland, it being
then determined to start a works in some part of England
where cheap coal could be obtained, and test the process on a
large scale. A small experimental plant was then set up in the
early part of 1887 on Farrington Road, London, where it was
inspected by many scientific men, among them Dr. John Hop-
kinson, F. R. S., who reported on the quantitative results
obtained ; a description of the process as here operated was
also written up for " Engineering." With the co-operation of
Major Ricarde-Seaver a larger plant was put up at Hope Mills,
Tydesley, in Lancashire, where the process was inspected and
reported on by Dr. George Gore, the electrician. After his
report we learn that the patents were acquired by the Alumin-
ium Syndicate, Limited, of London, a combination of capitalists
among whom are said to be the Rothschilds.
The aluminium compound used is commercial cryolite. It
is stated that the native mineral from Greenland contains on an
average, according to Dr. Kleiner's analysis, 96 per cent, of
pure cryolite, the remainder being moisture, silica, oxides of
iron and manganese. As pure cryolite contains 13 per cent,
of aluminium, the native mineral will contain 12^ per cent.,
♦English Patents, 8531, June 29, 1886, and 15322, Nov. 24, 1886.
REDUCTION OF ALUMINIUM COMPOUNDS.
349
all of which Dr. Kleiner claims to be able to extract. It is
further remarked that as soon as sufificient demand arises, an
artificial cryolite can be made at much less cost than that of the
native mineral, which now sells at ;^i8 to ;^20 a ton. The
rationale of the process consists in applying the electric current
in such a way that a small quantity of it generates heat and
keeps the electrolyte in fusion, while the larger quantity acts
electrolytically. Dry, powdered cryolite is packed around and
between carbon electrodes in a bauxite-lined iron crucible ; on
Fig. 35.
passing a current of high tension (80 to 100 volts) through the
electrodes, the cryolite is quickly fused by the heat of the arc
and becomes a conductor. As soon as the electrolyte is in
good fusion the tension is lowered to 50 volts, the quantity
being about 150 amperes, the arc ceases and the decomposi-
tion proceeds regularly for two or three hours until the bath is
35°
ALUMINIUM.
nearly exhausted. The evolved fluorine is said to attack the
bauxite, and by thus supplying aluminium to the bath extends
the time of an operation. In the first patent the negative car-
bon was inserted through the bottom of the melting cavity, the
positive dipping into the bath from above, (Fig. 35) but it was
found that while the ends of the positive carbon immersed in
the cryolite were unattacked, the part immediately over the
bath was rapidly corroded. In the second patent, therefore,
the positive electrode was circular and entirely immersed in
the cryolite, connection being made by ears which projected
through the side of the vessel. (Fig. 36.) As the carbons
Fig. 36.
are thus fixed, the preliminary fusion is accomplished by a
movable carbon rod suspended from above, passing through
the circular anode and used only for this purpose. The bath
being well fused and the current flowing freely between the
fixed carbons, the rod is withdrawn. The carbons are said to
be thus perfectly protected from corrosion, and able to serve
almost indefinitely. The melting pots finally used were or-
dinary black-lead crucibles, which are not usually injured at all,
since the fused part of the cryolite does not touch them, and
they last as many as 300 fusions. After the operation, the
carbons are lifted out of the bath and the contents cooled.
REDUCTION OF ALUMINIUM COMPOUNDS. 35 I
When solid, the crucibles are inverted and the contents fall
out. This residue is broken to coarse powder, the nodules of
aluminium picked out, melted in a crucible and cast into bars.
The coarse powder is then ground to fine dust. This powder
is more or less alkaline and contains a greater or less excess of
fluoride of sodium in proportion to the amount of aluminium
which has been taken out. If only a small proportion of the
metal has been extracted and the powder contains only a small
excess of sodium fluoride, it is used again without any pre-
paration in charging the crucibles ; but if as much as 5 or 6
per cent, of aluminium has been removed and the powder,
therefore, contains a large excess of sodium fluoride, it is
washed with water for a long time to remove that salt, which
slowly dissolves. The solution is reserved, while the powder
remaining is unchanged cryolite, and is used over. Dr. Gore
states that if the powder, electrodes and crucible are perfectly
dry, there is no escape of gas or vapor during the process ;
but if moisture is present, a small amount only of fumes of
hydrofluoric acid appear, and that there is no escape of fluorine
gas at any time. Dr. Kleiner hopes to soon dispense with the
interruption of the process, washing, etc., by regenerating
cryoHte in the crucible itself and so making the process con-
tinuous. One of the great advantages claimed is that the
aluminium is obtained in nodules, and not in fine powder; if it
was, it could not all be collected because it is so light, some of
it would float upon the water during the washing process and
be lost, and even when collected it could not be dried and
melted without considerable loss.
It has been found impossible in practice to obtain all the
aluminium from a given quantity of cryolite in less than two
fusions, for the sodium fluoride collecting in the bath hinders
the production of the metal. The proportion extracted by a
single fusion depends upon its duration. In the operations at
Tydesley, a fusion lasting 24 hours separated only 2^ per
cent, of aluminium, whereas the cryolite contained 12^ per
cent. At this rate, to extract the whole in two operations would
352 ALUMINIUM.
require two fusions of 6o hours each. As to the output, on an
average a current of 38 electric horse-power deposited 150
grammes of aluminium per hour, being a little over 3 grammes
per horse-power. Since a current of 50 volts and 150 amperes,
such as was stated above as the current in each pot, is equal to
50x^50 ^^ j^ electric H. P., it is probable that the 38 H. P. cur-
rent mentioned must have been used for four crucibles. Now,
the output of four crucibles, each with a current of 150 amperes,
should have been 0.00009135X150X4=0.0548 gramme per
second, or 197.3 grammes per hour; the difference between
this and the amount actually obtained, or 47.3 grammes, is the
amount of aluminium which was produced and then afterwards
lost either as fine shot-metal or powder, or dissolved again by
corroding elements in the bath. To calculate how the output
of 3 grammes per electric H. P. per hour compares with the
quantity of metal which this amount of energy should be able
to produce, we can assume that since it takes at most 4 volts to
decompose the aluminium fluoride, the four crucibles would
consume 16 volts in decomposition, being sixteen-fiftieths of
the total voltage employed. Since the amperes only produced
150 grammes out of 197.3 theoretically possible, the efhciency
over all is only
16 150 1
As to the purity of the metal obtained, the process is met at
the outset by the silica and iron oxide in the cryolite, which are
probably all reduced with the first few grammes of aluminium
thrown down. This can possibly be remedied by using a purer
artificial cryolite ; the impurities cannot generally be separated
from the natural mineral. Then there are impurities of a simi-
lar nature coming from the carbons used, and which are gene-
rally present if especial pains are not taken to get very pure ma-
terials for making them. Dr. Kleiner's early attempts produced
metal of 85 to 95 per cent, purity, but he stated in 1889 that it
was uniformly 95 to 98 per cent., and being put on the market in
REDUCTION OF ALUMINIUM COMPOUNDS. 353
competition with other commercial brands. It appears, how-
ever, from a consideration of the preceding data, that the pro-
cess could not produce aluminium much cheaper than 12 shil-
lings a pound, and it was therefore abandoned in 1890. It may
be observed that the mechanical arrangements for carrying on
this process, as above outlined, could not stand comparison with
the present forms of apparatus in use by the Hall and Heroult
processes.
Lossier's Method.
* This is a device for decomposing the natural silicates by
electricity and obtaining their aluminium. The bath is com-
posed of pure aluminium fluoride or of a mixture of this salt
and an alkaline chloride, and is kept molten in a round bot-
tomed crucible placed in a furnace. The electrodes are of dense
carbon and are separated in the crucible by a partition reach-
ing beneath the surface of the bath. The positive electrode is
furnished with a jacket or thick coating of some aluminium sili-
cate plastered on moist and well dried before use. When the
current is passed, the aluminium fluoride yields up its fluorine at
this pole and its aluminium at the other. The fluorine com-
bines with the aluminium silicate, forming on the one hand alu-
minium fluoride, which regenerates the bath, on the other silicon
fluoride and carbonic oxide, which escape as gases. The metal
liberated at the negative pole is lighter than the fused bath, and
therefore rises to the surface.
M. Grabau cites as one of the recommendations of aluminium
fluoride for use in his process (p. 295), that it is quite infusible,
so it would appear that Lossier has made a mistake in suppos-
ing that it could be melted alone in a crucible. It would, how-
ever, make a very fusible bath when the alkali chloride was
added. It is probable that the carrying out of this method
would develop great trouble from the attacking of the crucible
by the very corrosive bath, the disintegration of the carbons,
which would cause much trouble at the negative pole especially,
* German Patent (D. R. P.), No. 31089.
23
354 ALUMINIUM.
and the oxidation of the fluid aluminium on the surface of the
bath. The process has never been attempted on a large scale,
and it is very unlikely that it ever will be.
OmhoKs Furnace.
I. Omholt and the firm Bottiger and Seidler, of Gossnitz, have
patented the following apparatus for the continuous electrolysis
of aluminium chloride:* —
The bed of a reverberatory furnace is divided by transverse
partitions into two compartments, in each of which are two re-
torts semi-circular in section, lying side by side horizontally
across the furnace, with the circular part up. They are sup-
ported on refractory pillars so that their open side is a small
distance above the floor of the furnace. The aluminium com-
pound being melted on the hearth, it stands to the same depth
in both retorts, and if the electrodes are passed through the
bottom of the hearth they may remain entirely submerged in
molten salt and each under its own retort cover. The metal
therefore collects in a liquid state under one retort and the
chlorine under the other, both being preserved from contact or
mixture with the furnace gases by the lock of molten salt. The
chlorine can thus be led away by a pipe, and utilized, while the
aluminium collects without loss, and is removed at convenient
intervals.
The great cost of making aluminium chloride will probably
prevent it ever being used again in the metallurgy of alumin-
ium, but the form of furnace described above may possibly be
utilized in operating the decomposition of some other aluminium
salt, such as the double sulphide with soda.
Minefs Process (1887).
This consists, according to the patent specification, f in the
electrolysis of a mixture of sodium chloride with aluminium
fluoride or with the separate or double fluorides of aluminium
* German Patent (D. R. P.), No. 34728.
t English Patent, No. 10057, July r8, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 355
1
and sodium, melted in a non-metallic crucible or in a metallic
one inclosed in a thin refractory jacket to avoid filtration, the
aluminium fluoride decomposed being regenerated by causing
the fluorine vapors evolved to act on bauxite or alumina
placed somewhere about the anode. The details of the appar-
atus and bath are as follows : —
Disposition of the Apparatus. — The pots or crucibles used
may be of refractory earth, plumbago, or of metal, and in cases
where an alloy is required the crucible itself serves as an elec-
trode. None of these, however, resist the corrosive power of
the electrolyte and would under ordinary conditions be quickly
destroyed. To overcome this difficulty two special devices are
employed. When alloys are to be made directly, the pot is
cast of the metal with which the aluminium is to be combined.
It is shaped with a sloping bottom and provided with a tap
hole. The pot is encased in thin brickwork and is then made
the negative electrode, the positive being two carbon rods
dipped into the bath. As soon as the current is passed alu-
minium is deposited on the walls of the pot, forming a rich
alloy with the metal of which the pot is made (iron or copper).
When this coating becomes sufficiently rich in aluminium, the
heat of the bath melts it and it trickles down and collects at the
bottom. After a certain time, the alloy can be tapped out
regularly at intervals without interrupting the electrolysis. The
metal thus obtained is principally aluminium containing a few
per cent, of the metal of the pot, which is of no consequence,
since the end to be finally attained is the production of an alloy
with a smaller quantity of aluminium. When pure aluminium is
to be obtained, an ingenious device is used to protect the metal
from contamination by the metal of the pot. Carbon plates, A
and C (Fig. 37), serve as anode and cathode, the cathode stand-
ing upright in a small crucible placed upon a plate resting on
the bottom of the pot. This crucible and plate are made from
'carbon blocks or from fused alumina or fluorspar moulded into
the shape desired. As the metal is set free it trickles down
the cathode and is caught in the crucible or cup, thus being
356
ALUMINIUM.
prevented from spreading out over the bottom of the pot. To
prevent the bath from corroding the pot, the wire R is passed
from the latter to the negative pole of the circuit. The pot is
thus made part of the negative electrode, but it is not intended
that much of the current should pass through it, so a resistance
coil is interposed between it and the battery or dynamo, so that
Fig. 37.
the derived current passing through the sides of the pot is only
5 to 10 per cent, of the whole current. The effect of this is
that a small amount of aluminium is deposited on and alloys
with the sides of the vessel, which protects the latter from cor-
rosion and is only feebly acted upon by the bath. The metal
deposited in the crucible is thus kept nearly pure, while a small
amount of alloy falls to the bottom of the pot and is poured
out after the crucible has been removed. When it is wished to
obtain the purest aluminium, the intensity of the derived cur-
rent passing through the pot is increased by removing part of
the resistance interposed between it and the negative wire, thus
also decreasing the intensity of the principal current. The
REDUCTION OF ALUMINIUM COMPOUNDS. 357
nature of the electrodes proper may be varied. For producing
pure aluminium the anode is carbon, the cathode carbon, and
the pot either of copper or iron ; for producing copper alloys
the anode may be either carbon or bright copper, and the
cathode (pot) of carbon or copper; for producing iron alloys
the anode may be either carbon or iron, while the vessel used
as cathode is either of cast-iron or plumbago.
Composition and properties of the baths. — Minet has made
more careful electrical measurements on these fused baths than
any other metallurgist, a point of particular importance in his
experiments being the accurate measurement of the tempera-
tures by means of a Le Chatellier electric pyrometer. On this
account his result^re a valuable contribution to the knowledge
of the present electrolytic processes, and are therefore worth
repeating in extenso. Minet first experimented with a bath of
Aluminium-sodium chloride 40 parts.
Sodium chloride 60 "
He says of the working of this mixture that it gives rise to
abundant vapors, which are very disagreeable. In consequence,
the bath becomes quickly impoverished in aluminium chloride,
it becomes pasty, and can only be liquefied by raising the tem-
perature almost to the melting point of sodium chloride. It is
difficult under these conditions to produce regular and continu-
ous electrolysis.
Minet obtained much better results with aluminium fluoride.
He mixed cryolite with common salt in the following propor-
tions :
Cryolite 37-5 parts.
Sodium chloride 62.5 "
giving a mixture whose formula would be AlFgSNaF + 6NaCl.
This mixture has the following properties :
Melting point 675° C.
Vapors given off at 1056° C.
Specific gravity at 829° C 1.76
Specific resistance at 870° C 0.32 ohms.
3S8 ALUMINIUM.
The last datum means that a column of the electrolyte i
centimetre square and i centimetre long would give 0.32 ohms
resistance to the passage of the current. If the section of the
electrolyte through which the current passed averaged 750
square centimetres, and the electrodes averaged 6 centimetres
apart, the total resistance of the bath would be
0.32 X ^0.0026 ohms:
750
and if the current was 1 500 amperes, the voltage absorbed by
the electrical conduction-resistance of the bath would be
0.0026 X 1500 = 3.9 volts.
The specific resistance was found to decrease about 0.07 per
cent, for every degree rise of temperature above 870°, or 7 per
cent, for every lOO degrees.
If this bath were simply electrolyzed, fluorine would be dis-
engaged, escaping into the air as carbon fluoride, CF4, while
the bath would become poorer in aluminium fluoride. If cryo-
lite alone were added during the process, sodium fluoride would
accumulate in the bath, and after a certain time sodium would
be set free. If the bath is renewed by adding aluminium fluor-
ide, this inconvenience is obviated, but there still remains the
question of suppressing the noxious fluoride vapors set free. If
the bath is renewed by placing alumina in the state of fine pow-
der in the bath, dropping it especially around the anode, the
fluorine set free may reform aluminium fluoride by attacking
the alumina, setting free oxygen, which combines with the car-
bon anode to form carbonic oxide. If the fluorine were not
completely absorbed by the alumina, the amount escaping would
have to be made up for by adding aluminium fluoride to the
bath. The bath should therefore be fed by both alumina and
aluminium fluoride.
The above contains Minet's views of what takes place when
alumina is added to the fluoride bath. He does not admit that
any alumina can be really dissolved in the bath and be electro-
REDUCTION OF ALUMINIUM COMPOUNDS. 359
lyzed as alumina (the view taken by Hall). Minet, in fact,
maintains that when alumina is added to molten cryolite it
sinks through it and remains undissolved, as, for instance, very
fine marble dust would in water. Such, however, is not the
experience of other investigators. According to numerous
experiments by Hall and others using the present electrolytic
processes, as well as some made by the writer, finely-divided
alumina appears to dissolve in molten cryolite exactly as sugar
does in water, and there is even a saturation point, at about 30
per cent., above which no more dissolves. The bath containing
alumina forms to all appearances a homogeneous liquid.
Driven from their first position, the adherents to Minet's views,
having allowed that a homogeneous liquid bath does result, as-
sert that the alumina is only mechanically suspended, like
clay in muddy water, and that in this condition it is carried to
the anode and unites with the fluorine set free. Such a view,
however, is also erroneous, because regeneration in such a man-
ner could not be anything like complete, and considerable
amounts of fluorine would escape ; yet in the Hall process,
when the operation is properly conducted, not a trace of fluoride
gas escapes. Regeneration by mechanically-suspended alu-
mina could not possibly be so complete.
We shall continue describing Minet's experiments, asking that
it be remembered, however, that we regard as erroneous his
view that aluminium fluoride is the substance immediately de-
composed by the current when alumina is present.
Taking the bath already described, with electrodes of such
size and distance apart that the conduction-resistance at 900°
was 0.0044 ohms, the following results were obtained : —
Temperature.
Electromotive force
Conduction-resistance
for decomposition.
of the bath.
900°
2.4 volts
.0044 ohms
1000°
2.34 "
.0033 "
1100°
2.17 "
.0025 "
If V' = the voltage required for decomposition,
V° = the voltage required for conduction,
V = the total voltage absorbed by the bath,
A =; the amperage of the current.
then [V = VI -(- AV".]
36o
ALUMINIUM.
We can thus calculate the voltage required to send through
this bath any number of amperes at a given temperature.
Thus, for lOO or looo amperes the voltage absorbed per bath
would be as follows :
Temperature. Amperes. Voltage for
decomposition.
900"
I0CX3°
1 100"
100
2.4
1000
2.4
100
2.34
1000
2-34
100
2.17
1000
2.17
iltage for
Total
Per cent, of total
aduction
iistance.
voltage.
voltage absorbed
in conduction re-
sistance.
0.44
2.88
«5
4.40
6.80
65
0-33
2.67
12
3-30
5.64
59
0.25
2.42
13
2.50
4.67
54
It thus appears that, using a bath of a given size, the voltage
required to send lOOO amperes through it is only 2 to 2.5 times
that required for 100 amperes. Since the power required is
just in the same ratio, it follows that it is economical to send as
large a current as practicable through a bath of a given size.
The last column shows us the percentage of the energy of the
current which will be converted into heat. It follows from
these figures that the heating effect of the current increases
very rapidly with its quantity, so that a given number of
amperes will supply enough heat to keep the bath molten with-
out exterior heat; more than this number would, in fact, raise
the temperature of the bath too high, and this limits the size of
the current which it is practicable to send through a bath of a
given size.
Minet also found that when such a bath contained salts of
iron and silicon, which are weaker compounds than aluminium
or sodium salts, a current of carefully regulated low voltage, and
consequently of low density, would first separate these com-
pletely. An experiment made with a bath in which the anode
surface was 500 square centimetres, and gradually increasing
the voltage, gave the following successive results :
REDUCTION OF ALUMINIUM COMPOUNDS. 36 1
Total Amperes Amperes per Electro-motive Nature of the
voltage passing. sq. c. m. of force of decom- metal deposited.
used.
anode.
position (volts).
I.2I
75
o.is
0.54
Iron.
1.68
100
0.20
0.7s
Iron ( traces of silicon) .
2.48
125
0.25
1-37
Ferro-silicon.
2.89
150
0.30
1.54
Ferro-silicon (traces of aluminium)
2.94
15°
0.30
1.74
Silicon-aluminium (traces of iron) .
4.27
250
0.50
2.IS
Aluminium (traces of silicon) .
6.85
500
1. 00
2.50
Aluminium (traces of sodium).
The conduction-resistance of the bath remained very nearly
constant throughout.
In a large number of experiments, the amount of metal actu-
ally obtained was 50 to 80 per cent, of the amount which
the amperage of the current could theoretically produce, on an
average about 60 per cent. As for the power required, an
experiment lasting 24 hours, at a temperature of 1 160°, voltage
5.75, and amperes 1500, showed 21.5 grammes of aluminium
deposited per hour per electric horse-power used. Another
similar experiment, but with the electrodes closer together, the
voltage consequently less, and at a lower temperature, gave 31.9
grammes per horse-power-hour, which would be 0.765 kilos
(1.685 pounds) per electric horse-power per day. As the en-
ergy of one horse-power-day is equivalent to the energy of oxi-
dation of 2.1 kilos (4.63 pounds) of aluminium, the useful efifect
over all is 36.5 per cent.
Quality of metal. — When working for pure aluminium, about
three-fourths of the metal produced is taken from the crucible
in which the cathode stands, and is 98 to 99 per cent, pure ;
the other one-fourth has been deposited on the sides of the
cast-iron pot, and contains 10 to 20 per cent, of iron. It is
poured out and used for making ferro-aluminium.
Installations of the process. — Minet conducted his work at the
expense of Messrs. Bernard Bros. The first experiments were
made on the road Moulin Joli, in Paris, from March, 1887, to
March, 1888. This plant consisted of a 6 horse-power engine
and a Gramme dynamo capable of giving a current of 250
amperes at 12 volts tension. In the year named, this plant pro-
362 ALUMINIUM.
duced about 500 kilogrammes of pure aluminium and 1500
kilogrammes of ferro-aluminium or aluminium bronze.
The second installation was put up at Creil (Oise), com-
menced operations in April, 1888, and continued working until
October, 1891. This plant had a 40 horse-power engine, and
an Edison dynamo giving a current of 1200 amperes and 27.5
volts. Regularly it was run at only 16 volts, operating three
baths in tension, and at looo amperes. There were made here
daily about 10 kilos of pure aluminium and 5 to 6 kilos of alu-
minium in alloys.
At the first location, Minet was enabled to study experiment-
ally the purely scientific part of his processes ; the plant at
Creil enabled him to solve the practical details of the process.
In 1889, the Messrs. Bernard Bros, determined to work the
process on a large, industrial scale, and cast around for a loca-
tion having abundant water-power. It was decided to locate at
Saint Michel in Savoy. The stream utihzed is the Valoirette,
giving a volume of 3.5 cubic metres per second with a fall of
133 metres. This gives theoretically 6000 horse-power, and
should produce 4000 electric horse-power.
At this place were put up a turbine of 300 horse-power by
Bouvier of Grenoble, and a dynamo of 275 horse-power by
Hillairet-Huguet of Paris. The latter gives a current of 4000
amperes at 50 volts tension, aiid produces regularly about 150
kilos (330 pounds) of aluminium. It is stated that a 600 horse-
power dynamo, actuated by a lOOO horse-power turbine, was
started during 1894. Latest advices state that this estabUsh-
ment has been acquired by a French company formed to work
under the Hall patents.
Feldman's Method (1887).
A. Feldman, of Linden, Hannover, patented the following
electrolytic process : * —
A double fluoride of aluminium and an alkaline earth metal,
* English Patent, No. 12575, Sept. 16, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 363
mixed with an excess of a chloride of the latter group, is either
electrolyzed or reduced by sodium. The proportions of these
substances to be used are such as take place in the following
reactions : —
1. (AUF6+2SrF2) + 6SrCI.,=2Al+5SrF2+3SrCl2+6Cl.
2. (AljF6+2SrF2)+6SrCl2+6Na=2AH-sSrF2+3SrCl2+6NaCl.
The three equivalents of strontium chloride are found in prac-
tice to be most suitable. Potassium chloride may also be
added to increase the fluidity, but in this case the strontium
chloride must be in still greater excess.
Even if the above reactions and transpositions do take place,
the use of so much costly strontium salts would appear to ren-
der the process uneconomical.
Warren's Experiments (1887).
Mr. H. Warren, of the Everton Research Laboratory, has
outlined the following methods or suggestions, some of which
had already been carried out, and probably others have since
given useful ideas to workers in this line. The principle can
hardly be called new, since suggestions almost identical with
Mr. Warren's were made previously to his, but the latter's re-
sults are the first recorded in this particular direction:* "This
method of preparing alloys differs only slightly from the man-
ner in which amalgams of different metals are prepared, substi-
tuting for mercury the metals iron, copper, or zinc made liquid
by heat. These metals are melted, connected with the negative
pole of a battery, and the positive pole immersed in a bath of
molten salt floating on top of the melted metal. The apparatus
used is a deep, conical crucible, through the bottom of which
is inserted a graphite rod, projecting about one inch within, the
part outside being protected by an iron tube coated with borax.
As an example of the method, to prepare silicon bronze, copper
is melted in the crucible, a bath of potassium silico-fluoride is
* Chemical News, Oct. 7, 1887.
364 ALUMINIUM.
fused on top to a depth of about two inches. A thick platinum
wire dips into this salt, and on passing the electric current an
instantaneous action is seen, dense white vapors are evolved,
and all the silicon, as it is produced, unites with the copper,
forming a brittle alloy. Cryolite may be decomposed in like
manner if melted over zinc, forming an alloy of zinc and alu-
minium, from which the zinc can be distilled, leaving pure
aluminium."
Mr. Warren does not affirm that he has actually performed
the decomposition of cryolite in the way recommended, but
states that it may be done ; from which we would infer that he
simply supposed it could. A well-recorded experiment, then,
is needed to establish the truth of this statement. Neither does
he propose to make aluminium bronze in this way; it may be
that it was attempted and did not succeed, for Hampe states
that an experiment thus conducted did not furnish him alu-
minium bronze (p. 368).
Zdziarski' s Patent.
A. Zdziarski,* of Brest-Litowsk, Russia, appears to have
patented the above principle in 1884, for in his patent he states
that the metal to be alloyed with aluminium is melted in a
crucible, covered with a fusible compound of aluminium for a
flux (alumina and potassium carbonate may be used) and made
the negative pole of an electric current, the positive pole being
a carbon rod dipping in the flux.
Grabau's Apparatus.
LudwigGrabaUjf of Hannover, Germany, proposes to electro-
lyze a molten bath of cryolite mixed with sodium chloride. The
features of the apparatus used are an iron pot, in which the
bath is melted, and water-cooled cylinders surrounding both
electrodes, the jacket surrounding the negative one having a
* English Patent 3090, Feb. 11, 1884.
t German Patent (D. R. P.), No. 45012.
REDUCTION OF ALUMINIUM COMPOUNDS. 365
bottom, the other not. The object of these cylinders is, at the
positive electrode, to keep the liberated fluorine from attacking
the iron pot and so contaminating the bath, at the other pole
the liberated aluminium is kept from dropping to the bottom
of the pot, where it might take up iron, and can be removed
from the bath by simply lifting out the water-cooled cylinders
and carbon electrode. Mr. Grabau states that he has abandoned
this process because the inseparable impurities in the cryolite
produced impurities in the metal; it may be that with the pure
artificial cryolite, which he makes by his other processes (see
p. 171), this electrolytic process may again be taken up. (See
also p. 294.)
Rogers' Process (1887).
In July, 1887, the American Aluminium Company, of Mil-
waukee, was incorporated, with a capital stock of $1,000,000,
for the purpose of extracting aluminium by methods devised
by Prof. A. J. Rogers, a professor of chemistry in that city.
This gentleman had been working at the subject for three or
four years previous to that time, but it has not been until re-
cently that patents have been applied for, and they are still
pending.
The principle made use of has already been suggested in con-
nection with the production of sodium (p. 219). It is briefly,
that if molten sodium chloride is electrolyzed, using a molten
lead cathode, a lead-sodium alloy is produced. This alloy is
capable of reacting on molten cryolite, setting free aluminium,
which does not combine with the lead remaining because of its
weak affinity for that metal. If, then, cryolite is placed in the
bath with the sodium chloride, the two reactions take place at
once, and aluminium is produced. In the early part of 1888,
the company erected a small experimental plant, with a ten-
horse-power engine, with which the following experiments,
among many others, were made: —
I. *A current of 60 to 80 amperes was passed for several
* Proceedings of the Wisconsin Nat. His. Soc, April, 1889.
366 ALUMINIUM.
hours through a bath of cryolite melted in a crucible lined with
alumina, and using carbon rods 2^ inches in diameter as
electrodes, one dipping into the bath from above, the other
passing through the bottom of the crucible into the bath.
Only I or 2 grammes of aluminium were obtained, showing
that the separated metal was almost all redissolved or reunited
with fluorine. With the temperature very high, it was found
that sodium passed away from the bath without reducing the
cryolite.
2. A current averaging 54 amperes and 10 volts was passed
for five and a half hours through a mixture of I part cryolite
and 5 parts sodium chloride placed in a crucible with 3 70
grammes of molten lead in the bottom as the cathode. After
the experiment, 25 grammes of aluminium were found in
globules on top of the lead-sodium alloy. This latter alloy
contained some aluminium. The globules were about as pure
as ordinary commercial aluminium, and contained no lead or
sodium. From another experiment it was determined that the
lead-sodium alloy must first acquire a certain richness in
sodium before it will part with any of that metal to perform
the reduction of the cryolite. It was also found that a certain
temperature was necessary in order that aluminium be pro-
diiced at all.
3. A current of 75 amperes and about 5 volts suflficed to de-
compose the bath and to produce 105 grammes of aluminium
in seven hours. This would be nearly 30 grammes per hour
for each electric horse-power.
4. A current of 80 amperes and 24 volts was passed through
four crucibles connected in series for six hours, using a bath
of I part cryolite and 3 parts sodium chloride with 450
grammes of lead in each crucible. The crucibles were heated
regularly to a moderate temperature. There were obtained
altogether 250 grammes of quite pure aluminium. This would
be equal to 16 grammes per electric horse-power-hour.
" A large number of similar experiments afforded a return of
^ to I ^ lbs. of aluminium per electric horse-power per day.
REDUCTION OF ALUMINIUM COMPOUNDS. 367
The experimental plant now in operation consists of a 40 volt
— TOO ampere — dynamo, the current being sent through six pots
connected in series. When the bath is completely electrolyzed
the contents of the crucible are tapped ofif at the bottom and a
fresh supply of melted salt poured in quickly. The lead-
sodium alloy run off is put back into the crucibles, thus keep-
ing approximately constant in composition and going the
rounds continuously. With this apparatus, 3 to 4 lbs. of alu-
minium are produced regularly per day of 12 hours. As soon
as patents are obtained, it is the intention of the company to
put up a plant of 50 lbs. daily capacity, which can be easily
increased to any extent desired as the business expands."
Professor Rogers observes in regard to the apparatus that he
has tried various basic linings for his clay crucibles, but a paste
of hydrated alumina, well fired, has succeeded best. Some
"shrunk" magnesia lining, such as is used in basic steel fur-
naces, answered well, but could not be used because of the
amount of iron in it. Lime could not be used, as it fluxed
readily. The carbon rods lasted 48 hours without much cor-
rosion if protected from the air during electrolysis. Carbon
plates and cylinders were tried, but the solid rods gave the
best results. About 8 to 10 per cent, of aluminium can be
extracted from cryolite containing 12.85 P^r cent. The min-
eral used was obtained from the Pennsylvania Salt Company,
and was called pure, but it contained 2 per cent, of silica and
I per cent, of iron. These impurities pass largely into the
aluminium produced, but the company hoped to be able to
manufacture an artificial aluminium fluoride which will not
only be purer but less costly than this commercial cryolite.
Professor Rogers infers that pure aluminium fluoride would not
be an electrolyte, since the resistance of the bath increases as
the amount of other salts present decreases.
It is useless to base any accurate estimation of the cost of
aluminium by this process on the data given above, since they
were only for a small experimental plant. If, however, 75 per
cent, of the aluminium in cryolite can be extracted at the rate
368 ALUMINIUM.
of I lb. of metal per day per electric horse-power, and the
metal is free from lead and sodium, (a sample sent me was
of very fair quality,) it would seem that the process was in a
fair way to compete on an equal footing with the other electro-
lytic processes as operated in 1889, but it has been entirely
distanced by more recent developments.
Dr. Hampe on the Electrolysis of Cryolite.
Prof. W. Hampe, of Clausthal, whose name is a guarantee of
careful and exact observations, has written the following val-
uable information on this subject, in presenting which we will
also give the remarks of Dr. O. Schmidt, called forth by
Hampe's first article.
*" The electrolysis of a bath of cryolite mixed with sodium
and potassium chlorides, using a layer of melted copper in the
bottom of the crucible as cathode and a carbon rod as anode,
gave balls of melted sodium which floated on the surface and
burnt, but scarcely a trace of aluminium. Yet here the condi-
tions were most favorable to the production of the bronze. The
battery used consisted of twelve large zinc-iron elements.''
fDr. O. Schmidt, referring to this statement of Hampe's,
quotes an opposite experience. He fused cryolite and sodium
chloride together in a well-brasqued crucible in the proportions
indicated by the reaction
AUF6.6NaF+6NaCl=Al2Cle+i 2NaF.
At a clear red heat the bath becomes perfectly fluid and trans-
parent, and an anode of gas carbon and a cathode of sheet cop-
per are introduced. On passing the current the copper did not
melt but became covered with a film of deposited aluminium,
which in part penetrated the electrode and in part adhered to
the surface as a rich alloy which ultimately fused ofif and sank
to the bottom of the crucible. With a plate i to i ^ millimetres
thick, 10 per cent of its weight of aluminium could thus be de-
* Ghemiker Zeitung, xii., 391 (1888). fldem, xii., 457 (i
REDUCTION OF ALUMINIUM COMPOUNDS. 369
posited ; with one 3 millimetres thick, about 5 per cent. The
metal could be made perfectly homogeneous by subsequent
fusion in a graphite crucible. Dr. Schmidt further remarks
(evidently on the supposition that the reaction he gives actually
takes place) that on thermo-chemical grounds sodium would not
here be reduced, because while the molecule of sodium chloride
requires 97.3 calories for its decomposition, that of aluminium
chloride, — ^, requires only 80.4, and the current would attack
first the most easily decomposed. He also states that the cal-
culated difference of potential for the dissociation of aluminium
chloride which is ^'^ = 3.5 volts, was actually observed, and the
tension of the current must have been increased to about 4.5
volts to bring about the decomposition of the sodium chloride.*
Dr. Hampe's statement occasioned several other communica-
tions, which he considers and replies to in the following
article : f —
" Dr. O (whose name I withhold at his own request)
writes to me that by electrolyzing pure cryolite, using a nega-
ative pole of molten copper, he never obtained aluminium
bronze ; but, on the other hand, always obtained it if he used
the mixture of cryolite and sodium chloride mentioned by Dr.
Schmidt, and in place of the molten copper a thick stick of the
unfused metal. A letter from R. Gratzel, Hannover, contains a
similar confirmation of the latter observation. By electrolyzing
a mixture of 100 parts cryolite with 150 of sodium chloride in
* Aside from Hampe's subsequent remarks as to no aluminium chloride being
formed, we would further point out the fact that the decomposition of a chemically
equivalent quantity of aluminium chloride requires not — ^ = 80.4 calories, but
^"' °° or 53.6 calories, and the calculated difference of potential is properly -^^
or 2.3 volts. The fact that the observed tension was 3.5 volts shows that the current
was not strong enough to decompose the sodium chloride, as Schmidt observes, and
the fact that this current deposited aluminium would show that the heat of formation
of aluminium fluoride at this temperature cannot be greater than 23X3.5X6^483
(thousand) calories.
tChemiker Zeitung (Cothen), xiii., 29 and 49.
24
370 ALUMINIUM.
a graphite crucible holding 30 kilogrammes, aluminium bronze
dripped down from the ring-shaped copper cathode used, while
chlorine was freely disengaged at the carbon anode. But after
a time, long before the complete decomposition of the cryolite,
the formation of bronze stopped — even an attacking of that
already formed sometimes taking place. Pellets of an alloy
of sodium and aluminium appear on the surface and burn with
a white light.
" These comments excited me to further research in the mat-
ter. At first, it was necessary to consider or prove whether by
melting sodium chloride with cryolite a true chemical decom-
position took place, such as Dr. Schmidt supposed. If this
were the case, the very volatile aluminium chloride must neces-
sarily be mostly driven off on melting the mixture, and at a
temperature of 700° to 1000° C. there could not be any left in
it. But an experiment in a platinum retort showed that such a
reaction positively does not occur ; for neither was any alu-
minium chloride volatilized, nor did the residue contain any,
for on treatment with water, it gave up no trace of a soluble
aluminium compound. During the melting of the mixture, acid
vapors proceeded from the retort, and a small quantity of cryo-
lite was volatilized into the neck of the retort. Dr. Klochman
has shown that cryolite always contains quartz, even colorless,
transparent pieces, which to the naked eye appear perfectly
homogeneous, showing it when examined in thin sections under
the microscope, and on melting the mineral opportunity is
given for the following reactions :
SiOa 4- 4NaF = SiF, + 2Na20,
sNa^O + Al^Fe = 6NaF + AUO,,
as is rendered probable by the appearance of delicate crystals
of alumina on the inner surface of the retort just above the
fusion. The silicon fluoride probably passes away as silico-
fluoride of sodium.
" If cryolite is fused with such metallic chlorides that really do
REDUCTION OF ALUMINIUM COMPOUNDS. 37 1
bring about a decomposition, there is never any aluminium
chloride formed in these cases, but the sodium of the cryolite is
exchanged for the other metal. Dr. O , to whom I owe this
observation, fused cryolite with calcium chloride, hoping that
aluminium chloride would distil, but obtained instead crystals
of the calcium salt of alumina-fluoric acid ; thus,
NaeAljFi, + aCaClj = 6NaCl + CajAl^Fi^,
and in like manner can be obtained the analogous strontium or
barium compounds.
" Just as erroneous as the supposed production of aluminium
chloride are the other arguments advanced by Dr. Schmidt, re-
garding the reasons why sodium could not be set free. The
self-evident premises for the propositions are lacking, viz. : that
the two bodies compared are conductors. On the contrary, I
have previously shown* that aluminium chloride and bromide,
and more certainly its fluoride, belong to the non-conductors.
It follows, then, that there can remain no doubt that on elec-
trolyzing pure cryolite, or a mixture of it, with sodium chloride,
only sodium will be set free at first, either from sodium fluoride
or the more easily decomposable sodium chloride. The pres-
ence or absence of sodium chloride is consequently, chemically,
without significance.
" Since the experiments with solid cathodes gave aluminium,
while those with molten copper did not, these results being
independent of the presence or absence of sodium chloride, the
next attempt made was to seek for the cause of the different re-
sults in the differences of temperature. It was found that when
the electrolysis takes place at a temperature about the melting
point of copper, bubbles of sodium vapor rise and burn, and any
aluminium set free is so finely divided that it is attacked and
dissolved by the cryolite. To explain this action of the cryo-
lite it is necessary to admit the formation of a lower fluoride of
aluminium and sodium, such as I have recently proven the exist-
* Chemiker Zeitung (Cothen), xi., p. 934 (1887).
372 ALUMINIUM.
ence of.* The solution of the aluminium takes place according
to the following reaction:
Al^Fe.eNaF + Al = 3 (AlF2.2NaF) .
If the electrolysis takes place at a temperature so low that the
sodium separates out as a liquid (its volatilizing point is about
900°), large globules of aluminium will be produced, on which
the cryolite seems to exert no appreciable action. Nevertheless,
the yield of aluminium is much below the theoretical quantity
set free. Since pure copper melts at 1050°, and aluminium
bronze at 800°, the copper electrodes can remain unfused in the
bath while the bronze melts off as it forms, while the tempera-
ture can be low enough to keep the sodium in the liquid state.
By mixing sodium or potassium chlorides with the cryolite, the
melting point is lowered, or at a given temperature the bath is
more fluid, and so easier to work. When there is not enough
aluminium fluoride present in the bath to utilize all the sodium
liberated, the excess of sodium may form an alloy with some
aluminium, and rising to the surface, burn to waste. Since cry-
olite always contains silica, as previously explained, the bronze
thus obtained is always rendered hard with silicon, and is not of
much value commercially.''
Hall's Process.
Although Hall's patents were not issued by the patent office
until 1889, yet they were applied for in the middle of 1886, and
a commercial-sized plant was put up to work the process in
1888. Mr. Hall really discovered the principle on which his
process is based, and made some aluminium by it, on a small
scale, in February, 1886.
*Chem. Zeit. (Cothen), xiii., p. I (1879). Hampe melted together aluminium and
sodium fluorides in the proportions of one molecule of the first to four of the second,
and obtained what is apparently a lower fluoride than cryolite, in which aluminium
cannot be otherwise than diatomic, since analysis gives it the formula AlF2.2NaF.
This salt is similar in appearance and properties to cryolite. As there are still some
doubts, however, about this compound, the above explanation of the solution of alu-
minium by the cryolite need not be accepted as final.
REDUCTION OF AI,UMINIUM COMPOUNDS. 373
The inventor of this process, Charles M. Hall, of Oberlin,
Ohio, born in 1863, is a graduate of Oberlin College, and while
yet a student spent considerable time in experimenting on iso-
lating aluminium with the electric current. Less than a year
after leaving college, he conceived the following idea, which I
quote in his own words : " It occurred to me that if I could find
some stable solvent for alumina itself, which at a reasonable
and practicable temperature would dissolve the alumina by the
mere mingling of it with the solvent and allow the alumina so
dissolved to be electrolyzed out of it, leaving the solvent unaf-
fected, this would possibly be the best process which could be
devised for the manufacture of aluminium by electrolysis."
Many different salts were tried, to see if they possessed the
property required, among them the fluorides of calcium, mag-
nesium, sodium and potassium. These latter salts were the
only ones which gave any encouraging results, but the first two
were too hard to fuse, and they all dissolved only small quan-
tities of alumina. Hall next tried cryolite, the natural com-
pound of aluminium and sodium fluorides, and found that it
melted at a red heat and readily dissolved considerable alumina.
This was on February 10, 1886. On applying the electric cur-
rent to this bath he was not immediately successful ; but, at-
tributing the failure to the presence of silica in the crucible
lining, he tried a crucible with a carbon lining, and the experi-
ment was entirely successful. This was February 23, 1886, and
on July 9, of the same year. Hall applied for patents covering
his invention.
P. L. V. Heroult, of Paris, France, had, however, apphed for
a United States patent for substantially the same process on
May 22, 1886, and the patent ofifice declared an interference
and ordered both parties to give evidence as to the date of
invention and putting into practice. Hall was able to name
February 23, 1886, as the date on which he had put his inven-
tion into practical operation, while Heroult named only the
date of his French patent for the same invention, April 23,
1886. (See p. 386.) The result of these proceedings was
374 ALUMINIUM.
that a patent covering the process was issued to Hall on April
2, 1889. (Number 400,766.) This patent has claims cover-
ing the use of the following process :
1. Dissolving alumina in a fused bath composed of the
fluorides of aluminium and a metal more electropositive than
aluminium, and then passing an electric current through the
fused mass.
2. Dissolving alumina in a fused bath composed of the
fluorides of aluminium and sodium, and then passing an
electric current, by means of a carbonaceous anode, through
the fused mass.
In the specification of the patent, it is stated that the bath
preferred as a solvent contains :
Sodium fluoride 33.2 per cent.
Aluminium fluoride 66.8 per cent.
represented by the formula AlFj.NaF. A convenient method
of forming this bath consists in adding to the mineral cryolite
80.3 per cent, of its weight of aluminium fluoride, according to
the formula :
AlFs.sNaF + 2AIF3 = sCAlFs.NaF).
It is further stated that the bath may be fused in a crucible
or melting pot of iron or steel having a carbon lining, that the
positive electrode may be of carbon, copper, platinum or any
other suitable material, and the negative electrode a carbon
rod or the carbon lining of the bath. When the positive
electrode is carbon it is gradually consumed by the oxygen
liberated, but when copper is used a coating of copper oxide
is at once formed on it, which protects it from further oxidation
and causes free oxygen to be liberated. The tension required
to operate a bath is stated as 4 to 6 volts.
The above description may be taken as summarizing Hall's
process as developed by him at the date of application for his
patent, July, 1886. It is the writer's opinion that credit should
be given to both Hall and Heroult for originating this inven-
REDUCTION OF ALUMINIUM COMPOUNDS. 375
tion, as the principle was discovered independently by each at
very nearly the same time ; but in the subsequent development
and practical application of the invention, Hall in America
clearly outstripped Heroult in Europe.
Several other patents were subsequently applied for by Hall,
covering modifications of the original process, and these were
all issued with the original patent in 1889.* One covers the
use of a potassium-aluminium fluoride, AIF3.KF, instead of the
corresponding sodium salt, since it is much more fusible.
Also the addition of lithium fluoride to this salt. Another
covers the use of calcium and aluminium fluorides to form the
bath, such as 2AlF3.CaF2 or 2AlF3.3CaF2. Since this bath is of
higher specific gravity than molten aluminium, it is recom-
mended to add to it enough of the salt AIF3.KF to lower the
specific gravity below that of the aluminium. This is unneces-
sary if alloys of aluminium are to be made, in which case the
metal to be alloyed is made the negative electrode and the
alloy formed will be sufficiently heavy to sink. For making
alloys, the addition of barium fluoride to the bath is recom-
mended, as its high specific gravity is no inconvenience and it
is more fusible than the calcium or strontium fluorides. In
another of these patents, the bath specified has the formula
2(AlF3.3NaF) + aAlFj-CaFj, being made by melting together
cryolite, aluminium fluoride and fluorspar. When the bath
becomes clogged, by the settling out of a mushy deposit which
stops the current, the addition of 3 or 4 per cent, of anhydrous
calcium chloride is recommended as clearing or liquefying the
bath ; this addition is also said to lessen the disintegration of
the carbon anodes used.
As at present conducted, the process is worked according to
the original patent applied for in 1886, it having been found
that almost all the difficulties which the subsequent modifica-
tions were designed to overcome are entirely obviated by regu-
lar working on a large scale. It has been concluded from
* Numbers 400,664; 400,665; 400,666; 400,667; 400,766.
376 ALUMINIUM.
subsequent experience that almost all the difficulties met at
first were the results of the varying composition of the bath
and its irregular temperature, and were inherent in attempts to
work on a small scale.
From June, 1887, to the middle of 1888, Mr. Hall experi-
mented on his process at the Cowles' Bros, works at Lockport,
N. Y. His results here, working on a small scale, were not
sufficiently economical to induce that company to continue the
work. Mr. Hall, however, was confident that if the process
could be started on a large scale, aluminium could be made at
a cost very much below its selling price at that time. Leaving
Lockport, Mr. Hall went to Pittsburgh, and there, through the
influence of Mr. Romaine C. Cole, was successful in interesting
several capitalists, who contributed $20,000 in cash to put up a
works, and in September, 1888, organized the Pittsburgh Reduc-
tion Company, with a capital stock of $1,000,000. The con-
struction of the plant was immediately begun, and in Novem-
ber, 1888, aluminium was being produced at the rate of 50
pounds per day, which found a ready sale at $5 per pound,
leaving a handsome profit.
This plant was situated in Pittsburgh, and was operated by
steam-power, using coal for fuel. The machinery consisted of
two ordinary tubular boilers of sixty horse-power each, and a
Westinghouse " automatic " engine of 125 horse-power, running
two shunt-wound Westinghouse dynamos. These dynamos,
running at 1,000 revolutions, gave each a current of 1,000
amperes at 25 volts tension, and being coupled in parallel gave
a current of 2,000 amperes at full speed, or an average of 1,700
to 1,800 amperes at 16 volts on steady runs. This current was
passed through two reducing pots, coupled in series. These
pots were of cast-iron, 24 inches long, 16 inches wide and 20
inches deep, lined inside with a layer of hard-baked carbon 3
inches thick. From a copper bar above were suspended, by
^ inch copper rods, 6 to 10 three-inch carbon cylinders, each
originally 15 inches long. Each pot. held 200 to 300 pounds
of the electrolyte.
REDUCTION OF ALUMINIUM COMPOUNDS. 377
It was found that with apparatus and current of this size,
outside heating was not necessary; the heat generated by the
passage of the current being sufficient to keep the bath fused
at the proper temperature. Larger pots have since been used,
which will be described later, but as the operation in them is
exactly similar to that in the smaller ones, we will describe the
process at once.
The carbon lining of the pot forms the negative electrode,
connection being made to the iron casing. The fluoride salts
to form the bath are placed in the bottom of the cavity, the
carbon positive electrodes lowered until they touch the carbon
lining, and the current turned on. After a few minutes the
salt is melted and when red-hot in the vicinity of each carbon,
more salt is thrown around the carbons, or each carbon moved
up a little. In an hour or two sufficient salt has been melted to
form the bath, and the carbons have been brought out of direct
contact with the lining. The bath is now ready to dissolve
alumina, which is first sprinkled on top of the bath, and after
it has become hot and perfectly dry is stirred in.
The fumes which were arising from the decomposition of the
fluorine salts immediately cease, the voltage absorbed by the
bath falls, the number of amperes passing increases, and the
electrolysis of the dissolved alumina commences at once.
Powdered carbon (the stub ends of electrodes ground up) is
now placed on top of the bath in a layer about an inch thick,
serving to keep in the heat and so reduce the loss by radiation.
The carbon electrodes are clamped to a copper bar extending
the whole length of the pot (see Fig. 38), and if one part of
the bath becomes cooler than it should be, the carbons are
crowded together at that point and soon heat it up. In prac-
tice, the ends of the carbons are kept about 0.5 to i inch from
the lining, and each one carries about 250 to 300 amperes. If
more current than this passes through a carbon, as might happen
if it short-circuited, the copper rod becomes red-hot at its con-
nection with the carbon. As soon as this is observed, the
workman raises it slightly and so stops the extra current. The
378
ALUMINIUM.
carbons wear down gradually until only 3 or 4 inches long (the
depth of liquid bath is not over 6 inches) and must then be
replaced. The consumption of carbons in regular running is
less than one pound per pound of aluminium produced, show-
ing that they are burnt according to the reaction
AI.O, + 3C = 2AI + 3CO.
in which 102 parts of alumina would require 36 parts of car-
bon to combine with its oxygen, producing 54 parts of metal.
Fig. 38.
Theoretically, therefore, there is required || or ^ of a pound
of carbon to i pound of aluminium produced. The smal'l
amount over this actually used is consumed by the air with
which they inevitably come in contact.
In these small pots, a tension of 8 volts is required to oper-
ate each, at an amperage of 1800. If the voltage rises to 10
or more, it indicates that the alumina in the bath has become
exhausted, as is also shown by dense, irritating fluoride fumes.
REDUCTION OF ALUMINIUM COMPOUNDS. 3/9
The workman at once stirs in some of the alumina which is
always kept on top of the carbon covering, and the voltage
immediately falls. A delicate electrical instrument, set to a
certain voltage, gives immediate notice to the workman when
the bath is " out of ore." In regular working no fumes arise,
the carbon covering entirely conceals the red-hot fluid bath
beneath, and one can only convince himself that the bath is
really in operation by approaching and noticing the heat
radiated. When aluminium has accumulated for several hours,
it is ladled out with iron ladles well-rubbed with chalk or
plumbago. This operation gives rise to some fumes, and also
causes some of the electrolyte to be dipped out with the metal.
It has been suggested that a tap-hole should be provided, but
there was found great difficulty in keeping the pot tight when
this was tried, and the expedient of syphoning out the metal
has been found more practicable.
The crude ingots thus poured are re-melted in large crucibles ;
the re-melting plant is shown in Fig. 39.
The alumina used in this plant was from the German manu-
turer, Bergius, at Goldschmeiden, near Breslau, Silesia. As im-
ported, it contained about 33 per cent, of moisture, which is
driven off in a drying furnace. The cost of alumina was, in
1890, five cents a pound delivered in Pittsburgh, which would
make the dried alumina cost 7.5 cents per pound plus the cost
of calcining, which is not over 0.5 cent. If absolutely pure,
alumina should contain 52.94 per cent, of aluminium, but as
this calcined alumina usually contains about i per cent, of im-
purities, chiefly silica, there is only a little over 52 per cent, of
metal in it. An accurate account of several months' running
showed that the Hall process extracts a fraction over 50 per
cent, of metal from it. The alumina to furnish one pound of
aluminium therefore cost in 1890 about 16 cents. Since then,
the alumina is calcined in Germany before shipment, saving in
freight and customs dues, and can probably be laid down now
in New York at S cents per pound, making a cost of 10 cents
per pound of aluminium. There is, besides this, a small waste
38o
ALUMINIUM.
of bath material, which costs in the neighborhood of 7 cents per
pound to make, but since this does not in actual running
amount to over 2 pounds per 100 pounds of aluminium pro-
duced, this item of expense is quite small.
The output of these small pots was about one pound of
metal an hour from each, and they were kept in continued ope-
ration for several weeks at a time. If pure alumina is used,
Fig. 39.
,, "^^-^ /W''.
pure aluminium is produced ; that made from Bergius' alumina
averaging over 98 per cent. pure.
When a bath has been put into operation, the metal first
produced is contaminated with the silicon and iron present in
the bath material, but in a few days these are completely elim-
inated, and the bath material is almost chemically pure save for
the impurities introduced in the alumina.
If calcined, selected raw bauxite is used in the pots, the
metal produced averages 94 to 96 per cent, pure, and is sold for
REDUCTION OF ALUMINIUM COMPOUNDS. 38 1
use in iron and steel. Two analyses of such second quality-
metal gave :
Aluminium 94.16 9S'93
Silicon 4.36 2.01
Iron 1.48 2.06
As the material used only costs about i cent per pound
ready to put into the pots, and about 2^ pounds make one of
metal, this second quality metal costs about 7 cents less per
pound than the first quality.
An estimate of the cost of producing aluminium in this plant
in 1889, at the rate of fifty pounds per day, is as follows:
100 lbs. calcined alumina @ 8 cts =. $8.00
Fluorides for bath @ 7 cts = .50
Carbons = i.oo
50 horse-power engine = 15.00
2 engineers @ $3.00 per diem = 6.00
6 workmen @ ;j2.oo " = 12.00
Superintendence, office expenses, etc .= 10.00
Interest on plant, rent, etc ^ 7.50
Cost of about 50 lbs. of aluminium $60.00
In the early part of 1890 the plant was greatly enlarged.
The additions consisted of three Babcock and Wilcox boilers of
200 horse-power each, fired by natural gas ; two 200 Jiorse-
power Westinghouse compound engines ; two shunt-wound
Westinghouse dynamos running 325 revolutions per minute,
connected in parallel and giving a total current of 5000 amperes
at 50 volts tension. The conductors for this current were two
copper bars, 6 inches by 0.5 inch, giving a total cross-section
of 6 square inches. This gives a little over 800 amperes per
square inch section. This current operated five large pots con-
nected in series, averaging 9 volts to a pot. These large pots
are of one-quarter inch wrought iron, 5 feet long, 2% feet wide
and 2 feet deep, with a carbon lining 4 to 6 inches thick, and
supported on bricks to keep the bottom cool. Above are two
copper bars to which a double row of carbon electrodes are
clamped, there being 10 on each row or 20 in all. Each of
382 ALUMINIUM.
these pots produced 60 to 70 pounds of aluminium a day, mak-
ing the production of the entire plant in 1890 about 400
pounds per day. The cost of aluminium, working on this scale,
could scarcely have been over $0.75 per pound, since the
metal made here was sold during 1891 for $1.00 per pound.
During 1891, in order to obtain room to extend and cheapen
fuel, the entire plant was moved to New Kensington, Pa., on the
Allegheny River 18 miles from Pittsburgh. At this place the
capacity of the plant has been greatly increased, there being ap-
proximately 1500 horse-power employed, and the output having
been increased to lOOO pounds per day in 1893 and to nearly
2000 pounds per day in 1894. Since the selling price has been
reduced to $0.50 per pound, it is evident that the present
cost cannot be much over $0.40, if so high. Captain A. E.
Hunt, president of the company, is authority for saying that as
the process is operated on an increasing scale, and more exper-
ience is had in running it, the cost in the future will approxi-
mate $0.20 per pound, the lowest limit by this process.
In July, 1890, a plant to work Hall's process was put into
operation at Patricoft, Lancashire, England, with a capacity of
about 300 pounds of aluminium a day. This plant was in
operation until 1894, when competition from Switzerland com-
pelled it to close.
During 1894, the United States Company have been con-
structing a larger plant at Niagara Falls, being furnished power
by the Niagara Falls Power Co. A contract has been made to
take 6000 horse-power, and the plant, so far constructed, is as
follows : *
A 5000 horse-power turbine, in the Power Company's power-
house, runs a 5000 horse-power, low frequency, alternating
current Tesla dynamo. This machine, at full speed, gives two
currents of 2500 volts by 775 amperes each, alternating 50 times
per second. The exciting circuit is continuous, obtained from
the main circuit by a rotary transformer, and amounts to only
0.2 per cent, of the main current. The total current of 2500
*This plant was put into operation on August 26, 1895.
REDUCTION OF ALUMINIUM COMPOUNDS. 383
volts by 1550 amperes is conducted through an underground
tunnel one-half mile to the aluminium works, through copper
rope conductors, with a total section of 4.3 square inches, with
a drop in potential of 12 volts. At the works, the current is
first passed through a set of stationary transformers, each of
250 horse-power, in which the current is reduced from 2487
volts to 115 volts. The alternating current of 115 volts next
passes to rotary transformers, each of 500 horse-power and
taking the current from two stationary transformers. In these
the alternating current of 115 volts is changed to a direct cur-
rent of 160 volts, the quantity of current furnished by each
rotary transformer being 2500 amperes. These currents of
2500 amperes by 160 volts are conducted to the pot room on
copper bars with 1.25 square inch section, each passing through
a separate switch-board, on which are shunt ammeters and vol-
meters, and then passed to the pots. The buildings are all of
iron, the main reduction room being 180 by 85 feet.
It is not difScult to estimate what the output of the two works
will be. At Pittsburgh each horse-power of electrical energy
produced about 1.2 pounds of aluminium per day, at which rate
a 5000 horse-power plant should make 6000 pounds, equiva-
lent in round numbers to 1000 tons a year, the present value of
which is $1,000,000.
Reactions and efficiency of the process. — Taking the first small
plant, a current of 1800 amperes in two vats should theoreti-
cally produce 56.4 pounds of aluminium per day. As 50
pounds were obtained, on an average, the efficiency shown in
this direction is nearly 90 percent. As only about 2.5 volts
out of the 9 volts absorbed by the bath, is used in decomposing
the alumina, wc have about 30 per cent, of the current thus
utilized. The efficiency over all is therefore 90 per cent, of 30
per cent.=27 per cent. This means that the work of separat-
ing aluminium from oxygen represents 27 per cent, of the actual
energy of the current. The difference between 9 and 2.5, or
6.5 volts, is absorbed in the conduction resistance of the bath,
being converted into heat. This would give a heat develop-
384 ALUMINIUM.
ment of 6.25 X 1800x0.00024= 2.7 calories per second, or
9720 calories per hour. To this we may add the heat of
oxidation of the carbon to carbonic oxide, and we have the
total heat generated in the bath. A balance would show as
follows :
Heat Developed per Hour.
By electrical resistances 9720 calories.
Oxidation of the carbon 960 "
Total 10680 "
Heat Distribution per Hour.
Heating 2 pounds alumina to 900° C 250 calories.
Withdrawn with the aluminium 17S "
Lost by radiation and conduction 10265 "
Total 10680
As to the real reaction in the bath, by which aluminium is
liberated, several metallurgists have taken the ground that the
aluminium fluoride present is the substance primarily disso-
ciated by the current, and that the fluorine set free at the anode
immediately acts on the alumina present in solution and re-
forms aluminium fluoride, liberating oxygen, which then unites
with the carbon. According to this view the reactions are
2AIF3 + Current = 2AI + 6F.
MO3 + 6F = 2AIF, + 3O.
3C + 3O = 3CO.
This theory must assume either one of two things ; first,
that the alumina added never becomes an integral part of the
bath, but remains suspended mechanically; or, second, that if
the alumina really is part of the bath, it is a stronger com-
pound than aluminium fluoride, and therefore, the current
decomposes the latter. This theory, however, involves several
contradictions. If, for instance, alumina is really a stronger
compound than aluminium fluoride, how could the gaseous
REDUCTION OF ALUMINIUM COMPOUNDS. 385
fluorine decompose alumina, forming aluminium fluoride?
Since gaseous fluorine can decompose alumina, as was proven
by Moissan, it follows that alumina is therefore a weaker com-
pound than aluminium fluoride, and that when an electric cur-
rent is passed through a bath containing these two compounds
the alumina is necessarily the first to be decomposed. The
only refuge left for this theory is, then, to maintain that the
alumina is not truly dissolved in the bath, but is only me-
chanically suspended. This, however, is contrary to the way
in which the bath behaves. Absorption of the fluorine could
not possibly be as perfect in that case as it really is in practice.
Besides, an experiment of Mr. Hall's settles the case, it seems
to me, beyond question. On passing the current through an
anode of clean copper, it becomes immediately coated with a
layer of copper oxide. If fluorine were at all set free, it would
be liberated in immediate contact with the anode, and copper
fluoride must necessarily have been formed ; but no trace of
that salt is observed. It thus appears impossible to me that
the electric current does anything but dissociate oxygen from
aluminium.
It has been suggested that the alumina is dissolved in the
bath by forming aluminium oxy-fluoride, and that this is the
substance electrolyzed. This may or may not be true, but there
is up to the present time no positive proof for the theory, and
several circumstances against it. No chemist has as yet iso-
lated and analyzed any such salt. If such salt is formed, the
larger the proportion of aluminium fluoride in the bath, the
more alumina it ought to dissolve. But cryolite contains 40
per cent, of aluminium fluoride, and dissolves at least 25 per
cent, of its weight of alumina to a clear solution, while the salt
AlFg.NaF, containing 66 per cent, of aluminium fluoride, and
made by adding aluminum fluoride to cryolite, dissolves barely
10 per cent. Further, no evolution of heat or other signs of
chemical action are observed when dissolving alumina in the
bath. If such a salt exists in solution, the elements set free at
the anode must be oxygen and fluorine, but it is already shown
25
386 ALUMINIUM.
that no fluorine can be detected there even when using a cop-
per anode. So, while the theory of an oxy-fluoride may be
true, and facts unknown to us now may reconcile these appa-
rent contradictions, yet at present there is no positive proof to
give in its favor.
In connection with this process, the following determinations
by the writer of specific gravities, when cold and melted at a
red heat, of the substances used in the bath, are of interest : *
Cold, Molten
after fusion. at a red heat.
Commercial aluminium 2.66 2.54
Commercial cryolite from Greenland 2.92 2.08
Cryolite containing' all the alumina it can
dissolve 2.90 2.35
Cryolite-faluminium fluoride forming the
salt AlFj.NaF (Hall's preferred bath) .. . . 2.96 1 .97
Same as above, but containing all the alu-
mina it can dissolve 2.98 2.14
SaltAlF3.KF 2.35
Powdered calcined alumina 3.60
H'eroiMs Processes.
P. L. V. Heroult, of Paris, France, patented in 1886 the fol-
lowing process, t Alumina is fluxed with cryolite, the bath be-
ing contained in a carbon crucible serving as the negative
electrode, which is placed inside a larger crucible and the space
between filled with graphite. (Fig. 40.) The positive electrode
is of carbon and dips into the fluid material. The negative elec-
trode is of carbon, and connects with the graphite filling between
two crucibles. A cover having holes for the electrodes is
placed over the whole, and a layer of clay and loam packed on
top of the cover. A current of only 3 volts will produce de-
composition, and the alumina is alone decomposed, the cryolite
remaining unaltered. The aluminium collects in the bottom of
the crucible, and alumina is added from time to time to renew
the bath. To prepare alloys, a negative electrode is made of
* Journal of the Franklin Institute, July, 1894, p. 51.
t French patent, 175,711; April 23, 1886.
REDUCTION OF ALUMINIUM COMPOUNDS.
387
the metal to be alloyed, and dips into the bath, and as the
current passes the alloy is formed and falls melted to the bottom
of the crucible. A convenient strength of current for a crucible
20 centimetres deep by 14 centimetres in diameter inside, with
a carbon anode 5 centimetres in diameter, is found to be 400
amperes, with an electro-motive force of 20 to 25 volts.
The idea or principle involved in the above is exactly simi-
FiG. 40.
lar to Hall's process, and when Heroult applied for United
States patents in 1886 the two claims interfered, and the evi-
dence given in the patent ofHce showed Hall to be the prior in-
ventor, so that the process in this country belongs entirely to
Hall. (See Hall's process, p. 373.) It is evident that the pro-
cess was discovered by these two inventors, on opposite sides
of the ocean, at very nearly the same time, and entirely inde-
pendent of each other. Hall, however, kept on improving his
388 ALUMINIUM.
process until, in 1888, it was working on an industrial scale.
Heroult, on the other hand, virtually abandoned his process
for the time, and did not make any pure aluminium by it on a
commercial scale until the end of 1889, at which time Hall had
been selling aluminium for a year and Hall's patents had been
issued over six months. It appears very much as if Heroult
was not aware of the possibilities of his process until Hall's suc-
cess showed the way.
Meanwhile, Heroult had devised another method of produc-
ing aluminium alloys, and successfully established it on a com-
mercial scale. This process is as follows : * Pure alumina is
melted by the intense heat of a powerful electric current,
and then electrolyzed by the same current, using melted
copper beneath the alumina as the cathode. The product
is aluminium bronze. Alumina without copper or iron as
a cathode cannot be electrolyzed to produce pure aluminium,
as the metal produced would rise to the surface and be volatil-
ized by the intense heat.
The Societe Metallurgique Suisse, which acquired both of
H^roult's patents, put up a plant to work the alloy process on
a commercial scale in July, 1888. This firm had experimented
some time with Dr. Kleiner's process, but abandoned it about
the middle of 1887, to try H^roult's process, and with such
successful results that the plant about to be described was de-
cided on. The instalment consisted of two large dynamos con-
structed especially for this work by the Oerliken Engineering
Company, and directly coupled to a 300 horse-power Jonval
turbine situated between them and mounted on a horizontal
shaft. A separate dynamo of 300 amperes and 65 volts, driven
by a belt from a pulley upon the main shaft, is used to excite
the field magnets of the two large machies. These large dy-
namos were originally intended to give each a current of 6000
amperes at 20 volts electro-motive force when running at 180
revolutions per minute, but sufficient margin was allowed in the
* French patent, 1 70,003, April 15, 1887. English' patent, 7,426 (1887). U.S.
patent, 387,876, August 14, 1888. German patent, 47,165, December 8, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 389
Strength of the field to be able to work to 30 volts. They have
even worked up to 35 volts on unusual occasions without any-
undue heating. It happens sometimes that the end of the anode
touches the molten cathode, producing a short circuit, when the
current will suddenly rise to from 20,000 to 25,000 amperes,
without, however, damaging the machine.
The main conductors are naked copper cables, about 10 cen-
timetres diameter, and no special precautions are taken to insu-
late them, since the current is of comparatively low potential,
and a leakage of 100 amperes more or less in such a large cur-
rent is too insignificant to take the trouble to avoid. An am-
peremeter is placed in the main circuit, its dial being traversed
by an index about i metre long, which is closely watched by
the workman controlling the furnace.
The furnace or crucible first used consisted of an iron box
cast around a carbon block, the iron, on contracting by cool-
ing, securely gripping the surface of the carbon on all sides, and
thus insuring perfect contact and conduction of the current
from the cathode inside. This method was found only suitable
for small crucibles, and the next furnace was built up of carbon
slabs held together by a strong wrought-iron casing. The in-
terior depth of the crucible was 60 centimetres, length 50 and
breadth 35 centimetres, which would permit the introduction of
the carbon anode and leave a clear space of 4 centimetres all
around it horizontally. At the bottom of the cavity is a passage
to a tap-hole, D (Fig. 41), closed by the plug E, which is from
time to time withdrawn to run ofT the alloy. The carbon
anode, F, is suspended vertically above the crucible by pulleys
and chains, which permit it to be raised and lowered easily and
quickly. This anode is built up of large carbon slabs laid
so as to break joints, and securely fastened together by car-
bon pins. The whole bar is 250 centimetres long, with a
section 43 by 25 centimetres, and weighs complete 255 kilos.
The conductor is clamped to the anode by means of the cop-
per plates, G. The crucible is covered on top by carbon slabs,
H, H, 5 centimetres thick, leaving an opening just large enough
390
ALUMINIUM.
for the anode to pass through. The openings, y, y, closed by
the lids, K, K, serve for introducing fresh copper and alumina.
The materials used have just been mentioned. Electrolytic
or Lake Superior copper is used, the former being perhaps pre-
ferred if from a good manufacturer. The alumina is bought as
commercial hydrated alumina, costing in Europe 22 francs per
100 kilos (2 cents per lb.). This is, of course, calcined before
using, each 100 kilos furnishing about 65 kilos of alumina.
Corundum can be substituted for the artificial alumina ; some
from North Carolina was tried, and is said to have given even
more satisfactory results. Commercial bauxite has been used,
but since it contains more or less iron its use is confined to the
manufacture of ferro-aluminium. It is very cheap in Europe,
and requires no other preparation than simple calcining.
The operation is begun"! by placing copper, broken into
rather small pieces, in the crucible. The carbon anode is then
approached to the copper, which is quickly melted by the cur-
rent. The bath of fluid copper then becomes the negative
REDUCTION OF ALUMINIUM COMPOUNDS. 39 1
pole, and ore is immediately fed into the crucible. It also is
soon melted and floats on top of the copper. The electrolysis
now proceeds, care being taken that while the anode dips into
the molten ore, it does not touch the molten cathode. Par-
ticular stress is laid on the economy of keeping the distance
between the electrodes small, the reason given being that "the
space between, being filled with a layer of badly-conducting
molten ore, offers a resistance which increases with the dis-
tance ; and although resistance is necessary, in order that the
current should produce heat, it is not economical to have more
heat than is necessary to melt the ore — the work of separating
the metal from the oxygen being chiefly done by the electro-
lytic action of the current, and not by the high temperature."
In practice, this intervening space is not over 3 millimetres
(one-tenth of an inch). The workman in charge, by watching
the indications of the amperemeter, is enabled to maintain the
anode at its proper distance without any difficulty ; it is pro-
posed to do this regulating automatically by means of an
easily-constructed electrical device. The oxygen liberated
gradually burns away the anode, it being found that about one
kilo of the anode is consumed for every kilo of aluminium pro-
duced.
After the operation commences, the alumina and metal are
introduced alternately in small quantities at frequent and
regular intervals, and the alloy is tapped out about every
twelve hours. The only wear to which the crucible is sub-
jected is from the accidental admission of small quantities of
air; this waste is scarcely appreciable. All oxygen evolved
from the bath is evolved in contact with the anode and burns
it. When the anode has worn down until too short for further
use, it is replaced by another, the pieces of carbon left being
utilized for repairing, covering or building up the crucible.
The operation is kept up night and day, and it is generally
more than a day after starting before the crucible is thoroughly
up to its maximum heat and work. Two reliefs of five men
each operate the plant, one to superintend, one to prepare
392 ALUMINIUM.
and dry the alumina, a third to control the working of the cru-
cible by regulating the anode, a fourth to feed ore and metal
into the crucible, and the fifth to take care of the machinery,
prepare anodes, crucibles, etc. All five work together to
replace an anode or tap the crucible. A part of each tapping
is analyzed, to determine its percentage of aluminium. It is
the aim to produce as rich a bronze as possible at the first
operation (over 42 per cent, of aluminium has been reached),
and its subsequent dilution to any percentage desired is done
in any ordinary smelting furnace.
The average current supplied the crucible is 8000 amperes
and 28 volts, requiring an expenditure of a little over 300 horse-
power in the turbine. Starting cold it required, in one instance,
36 hours to produce 670 kilos of aluminium bronze containing
18.3 per cent, or 122.67 kilos of aluminium. Taking the cur-
rent as 300 electric horse-power, this would be a return of 1 1
grammes per hour or 0.264 kilos (0.6 lbs.) per day for each
electric horse-power. It is claimed by Mr. Heroult that the
furnace takes several days to attain its full efficiency, and that
when it does so the above charge can be worked in 12 hours,
which would triple the above production per horse-power. This
claim is backed by figures as to 271 hours of actual operation,
during which time the crucible cooled several times, but the
average over the whole period was 22^ grammes per hour or
0.544 kilo (1.2 lbs.) per day for each horse-power (163 kilos
of aluminium per day, total production). During actual opera-
tion at full efficiency, Mr. Heroult claims to get 35 to 40
grammes of aluminium per horse-power-hour, which would
mean 11 to 15 horse-power-hours per pound of aluminium, or
1.75 to 2.1 lbs. of aluminium per horse-power per day.
An idea of the percentage of the useful effect derived from the
current may be had very easily by considering that i electric
horse-power = 750 Watts = 644.4 calories of heat per hour.
(See p. 302.) As each gramme of aluminium evolves 7.25
calories in forming alumina, the production of i electric horse-
power in I hour (if its energy were utilized solely for separat-
REDUCTION OF ALUMINIUM COMPOUNDS. 393
ing aluminium from oxygen) would be 88.88 grammes.
Therefore the heat energy of the current is amply sufificient to
account for all the alumina decomposed, leaving over the heat
produced in the crucible by the union of oxygen with the car-
bon anode. Looking at the other side of the question, the
electrolytic action, we can easily calculate from the strength
of the current what it could perform. A current of 8000
amperes can liberate 2.68 kilos of aluminium per hour,* ac-
cording to the fundamental law of electro-deposition. If, then,
from the figures given, there were actually produced 3.3 kilos
and 6.8 kilos per hour, and 10.5 to 12 kilos are claimed when
up to the full efficiency, it is impossible that more than a frac-
tion of the aluminium is produced by electrolytic decomposition
of alumina, and the claim that the process is essentially electro-
lytic is without foundation. Similar calculations with the data
given with regard to Cowles' process will lead to exactly
similar conclusions, viz : that the absolute energy of the
current, if converted into its heat equivalent, is many times
more than sufficient to account for the decomposition of the
alumina on thermal grounds, but the amount of current used
will not suffice to explain the decomposition of the alumina as
being electrolytic. Therefore, in both these processes, the
oxygen is abstracted from alumina by carbon, the condition
allowing this to take place being primarily the extremely high
temperature and secondarily the fluidity of the alumina. The
presence of copper is immaterial to the reduction, as is clearly
shown in the Cowles process.
In November, 1888, the AUgemeine Electricitat Gesellschaft
of Berlin united with the Societe Electrometallurgique Suisse
in purchasing the Heroult Continental patents and organizing
the Aluminium Industrie Actien Gesellschaft, with a capital of
10,000,000 marks. Dr. Kiliani, the well-known electro-
metallurgical expert, was made manager of the works. On his
taking charge, a much larger plant was begun, including
foundries and machine shops for casting and utilizing ten tons
* N. B. Only one furnace was used on the circuit.
394
ALUMINIUM.
of bronze which it was intended to produce daily. This plant,
consisting of 8 crucibles, was put into operation in 1891, with
a capacity of 1000 kilos of alloyed aluminium daily.
About this time, Heroult in co-operation with Kiliani took
up again his process for producing pure aluminium, stimulated
thereto, no doubt, by the success of the Hall process in
America. They found that by modifying slightly the shape of
their crucibles .and using a bath of cryolite to dissolve the
alumina, the operation could be practically carried on in
their alloy type of furnace. The apparatus used for producing
pure aluminium is shown in Fig. 42. It will be noticed that
Fig. 42.
the carbon lining is not needed so thick as in the alloy fur-
naces, since the temperature' is so much lower; also that the
entire lining is not taken as the negative electrode, but a nega-
tive pole of carbon is inserted] through the bottom of the
crucible. This is the form of apparatus now in use at the
Swiss works, producing pure aluminium so cheaply that the
alloy process is nearly abandoned.
The plant at the Rhine Falls, as now operated, consists of-
REDUCTION OF ALUMINIUM COMPOUNDS. 395
the 300 horse-power turbine used since 1888, two 600 horse-
power turbines also of the Jonval type, put into operation in
1 89 1, and five other 610 horse-power turbines, four of which
were put into operation in May, 1893, and the other a few
months later. The water-rights obtained by the company in
1889 from the Canton Schaffhausen allowed it to take from the
Rhine 20 cubic metres (700 cubic feet) of water per second,
which at a fall of 20 metres gives an effect of 4000 horse-
power. The combined power of the above turbines exceeds
this, but one is always kept at rest and only seven regularly
run. The turbines are worked with an upward current of
water, and the dynamos are revolved horizontally like huge
tops above the turbine-shafts. The 600 horse-power dynamos
are of the Oerlikon make, and at 150 revolutions per minute
give a steady current of 7500 amperes at a tension of 55 volts.
The current is carried by massive copper conductors to the
crucibles.
This plant, working to its full capacity since the middle of
1893, turns out daily 2500 kilos (5500 pounds) of aluminium,
equal to 900 metric tons, a year. It is said that this amount is
not sufficient to supply the demand for the metal, and that the
company contemplates acquiring a large water power at Rhein-
felden, near Basle, and erecting there an even larger plant than
their present one.
In 1888 the Societe Electro-metallurgique Franfaise estab-
lished a works at Froges (Isere), 12 miles from Grenoble, to
manufacture aluminium alloys by the Heroult process. They
commenced selling alloys in the early part of 1889, and soon
after commenced making pure aluminium in the same manner
as has been described at Neuhausen. Their plant consists of
two turbines of 300 horse-power each, with two dynamos of
7000 amperes and 20 volts each, with an output estimated at
3000 kilos of alloys per day, which means 200 to 300 kilos of
aluminium. There are ten crucibles, five of which are shown
in Fig. 43. Each crucible requires about 10 volts to run it,
and produces i to 1.2 kilos of aluminium per hour, with an ex-
396
ALUMINIUM.
penditure of about 2 horse-power for each kilogramme pro-
duced per day. The output during 1893 was 50,000 kilos of
aluminium, over 97.5 per cent. pure.
In 1893 this company acquired a large water power at La
Praz, near Modane, and expected to be manufacturing alumin-
ium there in 1894.
The United States Aluminium Metal Co. was organized to
Fig. 43.
HEROULT ALLOY FURNACES AT FRI1GES, FR.ANCE.
work the Heroult alloy process in this country. An experi-
mental plant, under Mr. Heroult's personal direction, was
started at Bridgeport, Conn., in July, 1889, but the dynamo
proved inadequate, and was burnt out. A new one was ordered
from the Oerlikon Works, Zurich, which arrived the following
November, and was put to work early in 1890 at Boonton,
N. J. This dynamo was driven by water-power, and at 220
revolutions gave a current of 3500 amperes at 35 volts tension.
This current was sent through one crucible, shown in Fig. 44,
producing aluminium bronzes and ferro-aluminium. This
plant was only run for a few months, and no attempt has been
made to enlarge it to an industrial scale.
REDUCTION OF ALUMINIUM COMPOUNDS.
397
As the Neuhausen works are now (1895) selling aluminium
at $0.35 per pound in large quantities, it is interesting to at-
tempt to estimate what the cost is at present. They sell three
quahties of aluminium, designating them as follows: —
Flii. 44.
A HERdULT FURNACE.
CO.MrOSITION.
Silicon. Iron. Aluminium.
No. o 0.06 0.04 99.90
fO.lS 0.21 99.61
No. I '^
1 0.51 0.34 99.33
N0.2 1't ''^^ ""^V
1 3-82 3.34 92.84
The above price is for No. i metal. In fact, the cost of these
398 ALUMINIUM.
different grades differs only in the cost of the raw material, all
other expenses being the same. Making calculations on No i
grade, the cost at Neuhausen is probably as follows per kilo of
aluminium : —
2 kilos calcined alumina, @ fr. 0.40 0.80 francs.
0.3 kilos cryolite, @ fr. 0.75 0.25 "
1.2 kilos carbon electrode, @ fr. 0.30 0.35 "
Power — 40 H. P., hours 0.15 "
Labor and superintendence o-3S "
General cost, repairs, etc 0.50 "
2.40 "
The cost of No. i aluminium at Neuhausen is therefore at
present about 2.50 francs per kilo, or 23 cents per pound.
The additional cost of alumina for making No. O metal is prob-
ably 0.60 francs, and the lower cost of No. 2 metal, due to
using raw bauxite, about 0.40 francs. One of the ofiScers of
the company is quoted as saying that they could make No. i
aluminium for 2 francs per kilo if working a plant producing
10,000 kilos per day. A plant of such a size is one of the pos-
sibilities of the next five years.
Faure's Proposition.
Camille A. Faure, whose process of making aluminium
chloride is described on p. 166, proposes to obtain the metal
therefrom by electrolysis, using carbon electrodes. M. Faure
states that if the process is carried out on a large scale the
chlorine set free can be utilized to form bleaching powder, and
will thus nearly repay the whole cost of manufacturing the alu-
minium. Patents have been applied for, covering the details of
the electrolytic apparatus. The inventor states that he has de-
termined on a large scale that anhydrous, molten aluminium
chloride can be practically decomposed at 300° C. by an electro-
motive force of 5 volts, which comprises the force required for
actual decomposition and also that required to overcome the
resistance of the bath. At this rate, it would require an expen-
diture of 840 horse-power to produce 1000 kilos of aluminium
REDUCTION OF ALUMINIUM COMPOUNDS. 399
per day, which is about twice as efficient as present processes ;
but Mr. Faure bases his ideas of economy entirely on the value
of the bleaching powder obtained. He is sanguine of being
eventually able, if working on a sufficiently large scale, to make
aluminium at five cents per pound, and is still experimenting
in his laboratory at Grenoble.
Winkler's Patent.
August Winkler,* of Gorlitz, proposes to electrolyze a fusible
phosphate or borate of aluminium. This bath is made by
melting alumina or kaolin with phosphoric or boracic acid, the
proportions being such that the acid is saturated ; the separa-
tion of aluminium will not be hindered if alumina is added
continually to combine with the acid set free. Carbon elec-
trodes are used.
Willson's Process.
Mr. Willson, organizer of the Willson Aluminium Company,
of Brooklyn, N. Y., has patented the reduction of aluminium
alloys in an electrical furnace, as follows : The negative elec-
trode is a graphite crucible resting on a carbon slab to which
connection is made. The positive electrode is a hollow carbon
rod, passing through a hole in the cover. The operation is
similar in every respect to Heroult's alloy process (p. 390), ex-
cepting that reducing gases, as illuminating gas, are passed into
the crucible through the hollow anode during the operation, and
it is stated that the anode does not touch the molten material
beneath. Copper and corundum are charged, and alloys with
3 to 18 per cent, of aluminium are made. It is claimed that
the reducing gases perform the larger part of the reduction,
and in addition prevent the wasting away of the carbon anode.
A larger dynamo was constructed to work this process, and the
plant erected at Spray, N. C, near the corundum deposits, but
very little of the alloy has found its way into the market.
* German Patent, 45,824, May 15, 1888.
400 ALUMINIUM.
Grabau's Process*
This process proposes the electrolysis of a bath composed of
aluminium fluoride and caustic soda or potash or their carbon-
ates. The particular advantages claimed are that the alumin-
ium fluoride is procurable very pure by the inventor's chemical
processes (see p. 172), also that the alkaline salts are easily
procurable free from iron and silica, and if the operation is con-
ducted in a properly-constructed crucible, very pure aluminium
can be made. The electricity is supposed to break up the alu-
minium fluoride, the fluorine attacking the alkali forming an
alkaline fluoride, while the carbonic acid is driven off as gas.
If an excess of aluminium fluoride is used, cryolite will be left
in the bath, which can be sold as a by-product.
It does not seem probable that this process can ever compete
in cheapness with those based on the direct electrolysis of
alumina, nor make purer metal than can be made by the others
with a little extra care.
Bucherer's Process. \
This inventor claims the electrolysis of the double sulphides
of aluminium and an alkaline or alkaline-earth metal, mixed
with molten halogen salts. The double sulphide is made by
melting alumina with an alkaline polysulphide, sulphur and
carbon according to the reaction
3Na,S + AlA + 3C + 3S = Al,S3.3Na,S4-3CO.
This double sulphide dissolves easily in a fused bath of alka-
line or alkaline-earth chlorides or fluorides ; for instance, molten
sodium and potassium chlorides work well either alone or to-
gether. The bath needs only a feeble current to electrolyze it,
and produces very pure aluminium.
While these claims may be all true, yet it appears that con-
siderable expense would be incurred in making the sodium
* German Patent, 62851, June 13, 1891.
t German Patent, 63995, 1892.
REDUCTION OF ALUMINIUM COMPOUNDS. 4OI
polysulphide and in taking care of the sodium sulphide accum-
ulating in the bath. Pure alumina would have to be provided,
to start with, and the additional expense for chemicals is all in-
curred to save say 50 per cent, of the electrical power used in
other processes. It does not appear that the process will be
as cheap as those based on the direct electrolysis of alumina.
Another Sulphide Process.
The Aluminium Industrie Actien-Gesellschaft of Neuhausen
have taken out the German patent. No. 68909, in 1892. This
patent claims the electrolysis of aluminium sulphide dissolved
in a bath of alkaline or alkaHne-earth chlorides or fluorides,
being kept molten during electrolysis by the electrical heat.
The current needed for the bath is 2.5 to 3 volts if melted by
exterior heat, 5 volts if melted by the internal heating of the
current. As particular advantages are claimed^
1 . The carbon electrode is not destroyed, it being at a lower
temperature than that at which carbon and sulphur combine.
2. The small voltage required (theoretically, less than i volt
is needed for decomposition).
3. The aluminium sinks readily in the bath, avoiding short
circuits.
4. The sulphur set free can be condensed and used over in
making the aluminium sulphide.
26
CHAPTER XII.
REDUCTION OF ALUMINIUM COMPOUNDS BY OTHER MEANS
THAN SODIUM OR ELECTRICITY.
No very exact classification of these numerous propositions
can be made, since often many reducing agents are claimed in
one general process. Where such general statements are made,
the method will be found under the most prominent reducing
•agent named, with cross references under the other headings.
Reduction by Carbon without the Presence of other
Metals.
About the first attempt of this nature we can find record of
is the following article by M. Chapelle:* —
" When I heard of the experiments of Deville I desired to
repeat them, but having neither aluminium chloride nor sodium
to use I operated as follows : I put natural clay, pulverized and
mixed with ground sodium chloride and charcoal, into an ordi-
nary earthen crucible, and heated it in a reverberatory furnace,
with coke for fuel. I was not able to get a white heat. After
cooling, the crucible was broken, and gave a dry pulverulent
scoria, in which were disseminated a considerable quantity of
small globules about one-half a millimetre in diameter, and as
white as silver. They were malleable, insoluble in nitric or
cold hydrochloric acid, but at 6o° C. dissolved rapidly in the
latter with evolution of hydrogen ; the solution was colorless,
and gave with ammonia a gelatinous precipitate of hydrated
alumina. My numerous occupations did not permit me to
assure myself of the purity of the metal. Moreover, the ex-
periment was made under conditions which leave much to be
* Compt. -Rendus, 1854, vol. xxxviii., p. 358.
(402)
REDUCTION OF ALUMINIUM COMPOUNDS. 403
desired, but my intention is to continue my experiments, and
especially to operate at a higher temperature. In addressing
this note to the Academy I but desire to call the attention of
chemists to a process which is very simple and susceptible of
being improved. I hope before many days to be able to ex-
hibit larger globules than those which my first experiment
furnished."
M. Chapelle never did address any further communications
to the Academy on this subject, and we must presume that
further experiments did not confirm these first ones. The
author was once called upon to examine a slag full of small,
white metallic globules, the result of fusing slate-dust in a
similar manner to M. Chapelle's treatment of clay. They
proved to be globules of siliceous iron reduced from the iron
oxide present in the slate. It is not impossible that Chapelle's
metallic globules were something similar in composition to
these.
G. W. Reinar* states that the pyrophorous mass, which
results from igniting potash or soda alum with carbon, contains
a carboniferous alloy of aluminium with potassium or sodium,
from which the alkaline metal can be removed by weak nitric
acid.
The manager of an aluminium company in Kentucky claims
to produce pure aluminium by a process which the newspapers
state consists in smelting down clay and cryolite in a water-
jacketed cupola reducing furnace, it being also stated that the
aluminium is reduced so freely, and gathers under the slag so
well, that it is tapped from the furnace by means of an ordinary
syphon-tap. These are all the particulars which have been
made public. As to whether this company really does make
aluminium by any such process I am unable to assert; pure
aluminium has been sold by this company, but that it was made
by this company, or by any such process, is very doubtful.
O. M. Thowless,t of Newark, N. J., proposes to prepare a
* Wagner's Jahresb., 1859, p. 4.
t U. S. Patent, 370,220, Sept. 20, 1887. English Patent, 14,407 (1886).
404 ALUMINIUM.
solution of aluminium chloride by dissolving precipitated alu-
minium hydrate in hydrochloric acid. The solution is con-
centrated and mixed with chalk, coal, soda, and cryolite,
and the mass resulting heated in closed vessels to a strong,
red heat. It is also stated that aluminium fluoride may be
used instead of the chloride. The resulting fused mass is
powdered and washed, when it is said, that aluminium is ob-
tained in the residue.
According to a patent granted to Messrs. Pearson, Liddon,
and Pratt, of Birmingham,* an intimate mixture is made by
grinding together —
lOO parts cryolite.
50 " bauxite, kaolin or aluminium hydrate.
50 " calcium chloride, oxide or carbonate.
50 " coke or anthracite.
These are heated to incipient fusion in a carbon-lined furnace
or crucible for two hours, when the aluminium is said to be
produced and to exist finely disseminated through the mass. '
A mixture of 25 parts each of potassium and sodium chlorides
is then to be added and the heat raised to bright redness, when
the aluminium collects in the bottom of the crucible. A better
utilization of the fine powder is effected by washing it, drying,
and then pouring fused zinc upon it, which alloys with the alu-
minium and can be afterwards removed by distillation. If
melted copper is used, a bronze is obtained.
H. Bessemer, jr., of Westend,t tries to utilize the principle
of combustion under pressure in order to get a temperature
high enough to reduce alumina by carbon or a hydrocarbon
gas, the resulting aluminium vapor being rapidly cooled by
passing the products of the reaction through a small aperture
into a large chamber, the expansion cooling and condensing
the vapor. To conduct the process, an intimate mixture of
alumina and carbon is made into briquettes and put into a
* English Patent, 5,316, April 10, 1888.
t English Patent, 12,033, J"ly 29, 1889.
REDUCTION OF ALUMINIUM COMPOUNDS. 405
Strong iron vessel having a refractory lining and water-cooled
externally. Air heated in regenerative stoves and gaseous
fuel are forced into it at a pressure of three to four atmos-
pheres. A very high temperature is produced, sufficient it is
claimed to reduce the alumina. The products of combustion
and metallic vapor pass out through a fire-clay tube of small
size into a larger chamber, in which the aluminium vapor
condenses.
This process appears imaginary. Heating up the inside of
such a large vessel, water-cooled externally, to a temperature
sufficient to cause aluminium vapor to distil out of it, is ex-
tremely problematical, especially with the means of heating
employed.
Reduction by Carbon and Carbon Dioxide.
J. Morris,* of Uddington, claims to obtain aluminium by
treating an intimate mixture of alumina and charcoal with car-
bon dioxide. For this purpose, a solution of aluminium
chloride is mixed with powdered wood-charcoal or lampblack,
then evaporated till it forms a viscous mass which is shaped
into balls. During the evaporation hydrochloric acid is given
off. The residue consists of alumina intimately mixed with
carbon. The balls are dried, then treated with steam in appro-
priate vessels for the purpose of driving off all the chlorine,
care being taken to keep the temperature so high that the
steam is not condensed. The temperature is then raised so
that the tubes are at a low red heat, and dry carbon dioxide,
CO2, is then passed through. This gas is reduced by the car-
bon to carbonic oxide, CO, which now, as affirmed by Mr.
Morris, reduces the alumina. Although the quantity of car-
bonic oxide escaping is in general a good indication of the pro-
gress of the reduction, it is, nevertheless, not advisable to
continue heating the tubes or vessels until the evolution of this
gas has ceased, as in consequence of slight differences in the
consistency of the balls some of them give up all their carbon
* Dingier, 1883, vol. 259, p. 86. German Patent, No. 22,150, August 30, 1882.
406 ALUMINIUM.
sooner than others. The treatment with carbon dioxide lasts
about thirty hours when the substances are mixed in the pro-
portion of s parts carbon to 4 parts alumina. Morris states
further that the metal appears as a porous spongy mass, and is
freed from the residual alumina and particles of charcoal either
by smelting it, technically " burning it out," with cryolite as a
flux, or by mechanical treatment.
To produce any aluminium at all by such a process and at
such a low temperature, appears to me impossible.
Mr. P. A. Emanuel, of Aiken, S. C, had the idea of produc-
ing aluminium sulphide by passing carbon bi-sulphide vapor
over aluminium sulphate, and then reducing it by carbonic
oxide. The reactions proposed would be
A1,(S04)«-I- 4CS, - A1,S3 + 4COS + 4SO,
MS, + 3CO = 2AI + 3COS.
It seems to me that the first reaction would be very likely to
occur, because alumina alone would form the sulphide under
the same conditions. The reduction equation, however, is very
problematical. We do not know that carbon oxysulphide
would be produced by these substances, but even if it might be
formed, the reaction is thermally negative to an extent which
would render a high temperature necessary. In fact, the heat
deficit of the reaction is as follows :
Calories. Calories.
Decomposition of AljSj 124400
Decomposition of 3CO 87000
21 1400
Formation of 3COS i 148100
Deficit 63300
The reaction may possibly occur at a high temperature, but
I have no information that it has been experimentally accom-
plished.
Reduction by Hydrogen.
F. W. Gerhard * decomposes aluminium fluoride or cryolite
* Watts' Dictionary, article " Aluminium."
REDUCTION OF ALUMINIUM COMPOUNDS. 4O7
by subjecting them to hydrogen at a red heat. The aluminium
compound is placed in a number of shallow dishes of glazed
earthenware, each of which is surrounded by a number of other
dishes containing iron filings. These dishes are placed in an
oven previously heated to redness, hydrogen gas is then admit-
ted and the heat increased. Aluminium then separates, hydro-
fluoric acid, HF, being formed, but immediately taken up by
the iron filings, and thereby prevented from reacting on the
aluminium. To prevent the pressure of the gas from becoming
too great, an exit tube is provided, which may be opened or
closed at pleasure. This process, patented in England in 1856,
No. 2920, is ingenious, and some one said that it yielded good
results. The inventor, however, returned to the use of the
more costly reducing agent, sodium, which would seem to imply
that the hydrogen method had not quite fulfilled his expec-
tations.
(See also Comenge's processes.)
Quite recently the possibility of reducing alumina by hydro-
gen has been very neatly proven by Mr. H. Warren.* He
took a tube of fine-quality compressed lime and put into it
alumina, made by evaporating a solution of aluminium chloride
to dryness and calcining. He then passed pure, dry hydro-
gen gas through the tube, heating the outside with an oxyhy-
drogen blow-pipe flame, concentrating all the heat on one spot.
With a slow current of hydrogen there was no reduction, but
with a brisk current some water was formed, and there were
found, on cooling the tube and breaking it, distinct metallic
beads around the space of greatest heating. These were de-
tached, and found on examination to be pure aluminium. A
mixture of alumina and copper oxide readily gave under these
conditions aluminium bronze. Oxides of tungsten and manga-
nese were likewise reduced, but magnesia, silica and titanic
oxide were not affected.
* Chemical News, August 31, 1894, p. 102.
408 aluminium.
Reduction by Carburetted Hydrogen.
Mr. A. L. Fleury,* of Boston, mixes pure alumina with gas-
tar, resin, petroleum, or some such substance, making it into a
stiff paste which may be divided into pellets and dried in an
oven. They are then placed in a strong retort or tube which is
lined with a coating of plumbago. In this they are exposed to
a cherry-red heat. The retort must be sufficiently stong to
stand a pressure of from 25 to 30 lbs. per square inch, and be
so arranged that by means of a safety valve the necessary
amount of some hydrocarbon may be introduced into the re-
tort among the heated mixture, and a pressure of 20 to 30 lbs.
must be maintained. The gas is forced in by a force pump.
By this process the alumina is reduced, the metal remaining as
a spongy mass mixed with carbon. This mixture is remelted
with metallic zinc, and when the latter has collected the alu-
minium it is driven off by heat. The hydrocarbon gas under
pressure is the reducing agent. The time required for reduc-
ing 100 lbs. of alumina, earth, cryolite, or other compound of
aluminium, should not be more than four hours. When the
gas can be applied in a previously heated condition as well as
being strongly compressed, the reduction takes place in a still
shorter period.
Nothing is now heard of this process, and it has been pre-
sumably a failure. It is said that several thousand dollars were
expended by Mr. Fleury and his associates without making a
practical success of it. We should be glad to hear in the
future that their sacrifices have not been in vain, for the pro-
cess has possibilities in it which may some time be realized.
Petitjean f states that aluminium sulphide, or the double sul-
phide of aluminium and sodium (see p. 177), may be reduced
by putting them into a crucible or retort, through the bottom
of which is passed a stream of carburretted hydrogen. Some
solid or liquid hydrocarbon may be placed in the bottom of the
* Chemical News, June, 1869, p. 332.
tPolytechnisches Central Blatt., 1858, p. 888.
REDUCTION OF ALUMINIUM COMPOUNDS. 409
crucible. The aluminium is said to be thus separated from its
combination with sulphur. The powder must be mixed with
metallic filings, as iron, and melted in order to collect the alu-
minium. Or, metallic vapor may be passed into the retort in
place of carburetted hydrogen.
Messrs. Reillon, Montague, and Bourgerel* patent the pro-
duction of aluminium sulphide (see p. 177) and its reduction
by carburetted hydrogen exactly as above.
Lebedeff-f fluxes alumina in a graphite crucible with fluor-
spar, adding a double fluoride of aluminium and sodium to re-
duce the specific gravity of the bath, exactly as in the present
electrolytic processes. A reducing gas, as hydrogen or a
hydrocarbon, is then to be led into the crucible.
This method of reducing alumina has appeared so promising
to me, that, at my suggestion. Dr. Lisle, of Springfield, Ohio,
made some experiments of this kind, using natural gas as the
reducing agent. A graphite crucible was lined with carbon,
and cryolite melted in it. Alumina was then dissolved in the
bath until the cryolite was saturated. A current of heated
natural gas (90 parts methane to 10 parts hydrogen) was then
passed through for several hours, the temperature being a
bright red. No evidences of reduction were observed. The
experiment was also modified by passing in carbonic oxide,
with a like result. Although these experiments were fruitless,
yet I do not think that all the po.«sibilities have been exhausted,
and I heartily recommend this as a promising field for further
experiment.
R. E. Green, of Southall, England, | modified the experiment
by filling a retort with charcoal and then placing the alumina
fluxed with cryolite on top. On heating, the molten salt
trickles down over the carbon, while a reducing gas, hydrogen
or a hydrocarbon, is sent upwards through the retort from an
aperture below. Mr. Green, however, spoils his process and
* English Patent, 4576, March 28, 1887.
t German Patent, 57768 (1889).
J English Patent, 5914, April 6, 1889.
410 ALUMINIUM.
incidentally shows his ignorance of the properties of aluminium,
by recommending the addition of silica to the alumina, or the
use of some silica to make a slag. I might have been inclined
to believe that some aluminium could have been produced in
this retort, provided it had a carbon lining, but the addition of
silica would render such" a result very unlikely, or in any event,
a worthless metal would be obtained.
Reduction by Cyanogen.
According to Knowles' patent,* aluminium chloride is re-
duced by means of potassium or sodium cyanide, the former,
either fused or in the form of vapor, being brought in contact
with either the melted cyanide or its vapor. The patent further
states that pure alumina may be added to increase the product
The proportions necessary are in general —
3 equivalents of aluminium chloride.
3 to 9 " potassium or sodium cyanide.
4 to 9 " alumina.
Corbelli, of Florence,! patented the following method in
England : Common clay is freed from all foreign particles by
washing, then well dried. One hundred grammes of it are
mixed with six times its weight of concentrated sulphuric or
hydrochloric acid ; then the mixture is put in a crucible and
heated to 400° or 500° C. The mass resulting is mixed with
200 grammes of dry yellow prussiate of potash and 1 50 grammes
of common salt, and this mixture heated in a crucible to white-
ness. After cooling, the reduced aluminium is found in the
bottom of the crucible as a button.
According to Deville's experiments, this process will not give
any results. Watts remarks that any metal thus obtained must
be very impure, consisting chiefly of iron.
Lowthian Bell J attempted to obtain aluminium in his labora-
* Sir Francis C. Knowles, English Patent, 1857, No. 1742.
t English Patent, 1858, No. 142.
J Chemical Reactions in Iron Smelting, p. 230.
REDUCTION OF ALUMINIUM COMPOUNDS. 4II
tory by exposing to a high heat in a graphite crucible mixtures
of alumina and potassium cyanide, with and without carbon.
In no case was there a trace of the metal discovered.
Reduction by Double Reaction.
M. Comenge,* of Paris, produces aluminium sulphide (see p.
177) and reduces it by heating it with alumina or aluminium
sulphate in such proportions that sulphurous acid gas and alu-
minium may be the sole products. The mixture is heated to
redness on the bed of a reverberatory furnace, in an unoxidiz-
ing atmosphere, the reaction being furthered by agitation. It
is stated that the resulting mass may be treated in the way
commonly used in puddling spongy iron, and afterwards
pressed or rolled together. The reactions involved would be,
if they occurred,
AI2S3 + 2 AI2O3 = 6 Al + 3SO,.
A\& + Al2(S04)3 = 4Al + 6S0,.
It is also claimed that metallic alloys may be prepared by the
action of metallic sulphides on aluminium sulphate ; as, for
instance —
Al,(S04)3 + 3FeS = Al2Fe3-h 6SO2.
The sulphide is also reduced by hydrogen, iron, copper or
zinc, the reactions being
A1,S3 + 6H=2A1-|-3H2S.
Al2S3 + 3Fe = 2Al + 3FeS.
In the case of reduction by a metal, alloys are formed.
Mr. Niewerth's f process may be operated in his newly in-
vented furnace, but it may also be carried on in a crucible or
other form of furnace. The furnace alluded to consists of three
shaft furnaces, the outer ones well closed on top by iron covers,
and connected beneath by tubes with the bottom of the middle
* English Patent, 1858, No. 461, under name of J. H. Johnson.
fSci. Am. Suppl., Nov. 17, 1885.
412 ALUMINIUM.
one : the tubes being provided with closing valves. These
side-shafts are simply water-gas furnaces, delivering hot water-
gas to the central shaft, and by working the two alternately
supplying it with a continuous blast. The two producers are
first blown very hot by running a blast of air through them
with their tops open, then the cover of one is closed, the blast
shut off, steam turned on just under the cover, and water-gas
immediately passes from the tube at the bottom of the furnace
into the central shaft. The middle shaft has meanwhile been
filled with these three mixtures in their proper order: —
First: A mixture of sodium carbonate, carbon, sulphur and
alumina.
Second : Aluminium sulphate.
Third : A flux, preferably a mixture of sodium and potassium
chlorides.
This central shaft must be already strongly heated to com-
mence the operation ; it is best to fill it with coke before charg-
ing, and as soon as that is hot to put the charges in on the
coke. Coke may also be mixed with the charges, but it is not
necessary. The process then continues as follows : The water-
gas enters the bottom of the shaft at a very high temperature.
These highly heated gases, carbonic oxide and hydrogen, act
upon the charges so that the first breaks up into a combina-
tion of sodium sulphide and aluminium sulphide, from which,
by double reaction with the second charge of aluminium sul-
phate, free aluminium is produced. As the latter passes down
the shaft, it is melted and the flux assists in collecting it, but is
not absolutely necessary. Instead of producing this double
sulphide, pure aluminium sulphide might be used for the first
charge, or a mixture which would generate it ; or again pure
sulphide of sodium, potassium, copper, or any other metallic
sulphide which will produce the effect alone, in which case alu-
minium is obtained alloyed with the metal of the sulphide.
Instead of the first charge, a mixture of alumina, sulphur and
carbon might be introduced. Or the aluminium sulphate of
the second charge might be replaced by alumina. So one
REDUCTION OF ALUMINIUM COMPOUNDS. 413
charge may be sulphide of sodium, potassium or any other
metallic sulphide, and the second charge may be either alumina
or aluminium sulphate.
Messrs. Pearson, Turner, and Andrews* claim to produce
aluminium by heating silicate of alumina or compound sili-
cates of alumina and other bases with calcium fluoride and
sodium or potassium carbonate or hydrate, or all of these to-
gether. If other metals are added, alloys are obtained.
G. A. Faurie,f of St. Denis, France, claims that by making
an intimate mixture of alumina with carbon, moistening with
sulphuric acid (thereby producing some sulphate) and in-
tensely igniting the mass, aluminium is reduced, and globules
of aluminium picked out of the resulting powder. Another
metal may be added to produce an alloy.
Reduction in Presence of or by Copper.
Calvert and Johnson f obtained copper alloyed with alu-
minium by recourse to a similar chemical reaction to that em-
ployed to get their iron-aluminium alloy. Their mixture was
composed of —
20 equivalents of copper 640 parts.
8 (24) " aluminium chloride 1076 "
10 " lime 280 "
"We mixed these substances intimately together, and after
having subjected them to a high heat for one hour we found at
the bottom of the crucible a melted mass covered with cuprous
chloride, Cu^Clj, and in this mass small globules, which on
analysis contained 8.47 per cent, aluminium, corresponding to
the formula —
5 equivalents of copper 160 9i'96 per cent.
1 " " aluminium 14 8.04 "
100.00
♦English Patent, 12332, Sept. 12, 1887.
tU. S. Patent, July 22, 1890.
X Phil. Mag. 1855, X. 242.
414 ALUMINIUM.
" We made another mixture of aluminium chloride and cop-
per in the same proportions as above, but left out the lime.
We obtained an alloy in this case also, which contained 12.82
per cent, aluminium, corresponding to the formula —
3 equivalents of copper 96 87.27 per cent.
I " "aluminium 14 12.73 "
M. Evrard,* in order to make aluminium bronze, makes use
of an aluminous pig-iron. (It is not stated how this alumin-
ous pig-iron is made.) This is slowly heated to fusion, and
copper is added to the melted mass. Aluminium, having more
affinity for copper than for iron, abandons the latter and com-
bines with the copper. After the entire mass has been well
stirred, it is allowed to cool slowly so as to permit the bronze,
which is heavier than iron, to find its way to the bottom of the
crucible. M. Evrard makes silicon bronze in the same way by
using siliceous iron.
Benzont has patented the reduction of aluminium with cop-
per, forming an aluminium-copper-alloy. He mixes copper, or
oxidized copper, or cupric oxide, in the finest possible state,
with fine, powdered, pure alumina and charcoal, preferably
animal charcoal. The alumina and copper or copper oxide are
mixed in equivalent proportions, but an excess of charcoal is
used. The mixture is put in a crucible such as is used for
melting cast-steel, which is lined inside with charcoal. The
charge is covered with charcoal, and the crucible subjected first
to a temperature near the melting point of copper, until the
alumina is reduced, and then the heat is raised high enough to
melt down the alloy. In this way can be obtained a succession
of alloys, whose hardness and other qualities depend on the
percentage of aluminium in them. In order to obtain alloys of
a certain composition, it is best to produce first an alloy of the
highest attainable content of aluminium, to analyze it, and then
* Annales du Genie Civil, Mars, 1867, p. 189.
t Eng. Pat. 1858, No. 2753.
REDUCTION OF ALUMINIUM COMPOUNDS. 415
melt it with the required quantity of copper. The same pro-
cess can be used for the reduction of alumina with iron or ferric
oxide, only the carbon must in this case be in greater excess,
and a stronger heat kept up longer must be used than when
producing the copper-aluminium alloy. In contact with ferric
oxide the alumina is more easily reduced than with the metallic
iron.
Benzon further remarks that some of these alloys, as the
ferro-aluminium, may be subsequently treated so as to separate
out the metallic aluminium ; also that the iron alloy may be
mixed with steel in the melting pot, or suitable proportions of
alumina and carbon may be put into the melting pot. The iron
alloy may be useful for many purposes, especially in the manu-
facture of cast-steel.
The question opened up by Benzon's statements is whether
carbon reduces alumina in presence of copper. This has been
the subject of many careful experiments, and the verdict of the
most reliable observers is that at ordinary furnace temperatures
it does not. This principle has been the subject of numerous
patents, and before presenting the negative evidence on this
point we will review the claims made in these patents.
G. A. Faurie * states that he has succeeded in obtaining alu-
minium bronze by taking two parts of pure, finely-powdered
alumina, making it into a paste with one part of petroleum,
and then adding one part of sulphuric acid. When the yellow
color is uniform and the mass homogeneous, sulphur dioxide
begins to escape. The paste is then wrapped up in paper and
thrown into a crucible heated to full redness, where the petro-
leum is decomposed. The calcined product is cooled, powdered
and mixed with an equal weight of a metal in powder, e. g.,
copper. This mixture is put into a graphite crucible and
heated to whiteness in a furnace supplied with blast. Amidst
the black, metallic powder are found buttons of aluminium
alloy. In an English patent,! by Mr. Faurie, it is further
♦Comptes Rendus, 105, 494; Sept. 19, 1887.
t English patent 10,043, -^"g- '^i J887.
41 6 ALUMINIUM.
claimed that by making bricks out of the calcined alumina
mixture and alloying metal, and using similar bricks of lixi-
viated soda ashes mixed with tar for flux, the reduction can be
effected in a cupola.
Bolley,* at his laboratory in Zurich, and List.f at the royal
foundry at Augsburg, have shown that by following the process
claimed by Benzon the resulting copper contained either no
aluminium, or at most a trace.
In an experiment made by the author to test this point —
40 grammes of copper oxide and copper,
5 " alumina,
5 " charcoal,
were intimately mixed and finely powdered, put in a white-clay
crucible and covered with cryolite. The whole was slowly
heated to bright redness, and kept there for two hours. A
bright button was found at the bottom of the crucible. This
button was of the same specific gravity as pure copper, and a
qualitative test showed no trace of aluminium in it. A friend
of mine. Dr. Lisle, has repeated this experiment, taking the
metal produced and returning it to another operation and re-
peating this four times, but the resulting button scarcely showed
a trace of aluminium.
Dr. W. Hampe has also made an experimental test of this
subject with the following conclusions: J —
"The reduction of alumina by carbon, although often
patented, is on thermo-chemical grounds highly improbable ;
but since aluminium in alloying with copper, especially in the
proportions 9.7 parts of the former to 90.3 parts of the latter
(AlCu,), evolves much heat, it might be possible that the re-
action
AI.O3 + 3C + 8Cu - 2AlCu^ + 3CO
is exothermic. I therefore mixed alumina with the necessary
* Schweizer Polytechnisches Zeitschrift, i860, p. 16.
t Wagner's Jahresbericht, 1865, p, 23.
I Chemiker Zeitung (Cothen), xii. p. 391 C1888).
REDUCTION OF ALUMINIUM COMPOUNDS. 417
quantity of lamp-black and copper, in other cases evaporated
together to dryness solutions of aluminium and copper nitrates,
afterwards igniting them to oxides and adding the necessary
amount of carbon. These mixtures were put into gas-carbon
crucibles contained within plumbago pots with well-luted
covers, and heated in a Deville blast-furnace to a temperature
sufficient to frit together the quartz sand with which the space
between the two crucibles had been filled. In no case was
there a trace of aluminium produced, nor did the addition of
any flux for the alumina affect the result in any way."
The possibility of reducing aluminium sulphide by copper
has been generally decided affirmatively. M. Comenge
claimed that it was possible (see p. 411), Reichel * also stated
unreservedly that copper fillings performed the reduction at a
high temperature. In an experiment by the author, copper
foil was used instead of copper filings, the latter not being im-
mediately at hand, and the result was negative. As a similar
test with iron filings gave a good result, it seems quite probable
that copper would have performed the reduction under proper
conditions.
Andrew Mann,f of Twickenham, patents a process which
may be stated briefly as follows : Aluminium sulphate is
mixed with sodium chloride and heated until a reaction be-
gins to take place. The mass is mixed intimately with lime,
and to this mixture aluminium sulphate and ground coke
added. This is calcined, the powder mixed with a metal; as
copper, and melted down. In this case the slags are calcium
sulphide and copper chloride, while aluminium bronze is ob-
tained.
L. Q. Brin, of Paris,} claims to produce aluminium bronze by
the following process : Sheet copper is cleaned by pickling
and then covered with a mixture of 2 parts borax, 2 parts
common salt, and i part sodium carbonate, made into paste
♦ Journal fiir Pr. Chemie, xi. p. 55.
t English Patent, 9313, June 30, 1887; German Patent, 457SS' J^ec. 20, 18S7.
J English Patents, 3547-8-9, March 7, 1888; U. S. Patent, 410574, Sept. 10, 1889.
27
41 8 ALUMINIUM.
with water. The metal is then put into a reverberatory fur-
nace, heated to bright redness, and vapors of aluminium chlo-
ride led over it, carried in by a current of inert gas. (It is
stated that the vapors of aluminium chloride are produced by
heating in a retort a mixture of clay, salt and fluorspar.) The
aluminium compound is said to be decomposed, and the nas-
cent aluminium to combine with the copper, forming ij4 to 2
per cent, bronze at one operation, and by using this over it may
be enriched to any extent desired. In a modification of this
method, the coating put on the metal contains clay or other
earth rich in alumina. It is also stated that the metal thus
coated can be put into a cupola with alternate layers of fuel and
run down to an alloy.
Reduction by or in Presence of Iron.
M. Comenge claims that aluminium sulphide is reduced by
iron (see p. 41 1 ) ; the statement is repeated by a writer in the
" Chemical News," i860; F. Lauterborn* states that the reduc-
tion takes place at a red heat; Reichelj also records his success
in this reaction ; finally, the author has obtained encouraging
results.! I used a product containing 32.3 per cent, of alu-
minium sulphide. On mixing this intimately with fine iron
filings, and subjecting to a high heat for one and a half hours,
the product was a loose powder in which were small buttons of
metal. They were bright, yellower than iron, and contained by-
analysis 9.66 per cent, of aluminium.
H. Niewerth§ has patented the following process : " Ferro-
silicon is mixed with aluminium fluoride in proper proportions
and the mixture submitted to a suitable red or melting heat by
which the charge is decomposed into volatile silicon fluoride
(SiFi), iron and aluminium, the two latter forming an alloy.
In order to obtain the valuable alloy of aluminium and copper
* Dingier, 242, 70.
t Jrnl. fur Pr. Chemie, xi. 55.
I Graduating Thesis, Lehigh University, June, 1886.
§ Sci. Am. Suppl., Nov. 17, 1883.
REDUCTION OF ALUMINIUM COMPOUNDS. 419
from this iron aluminium alloy, the latter is melted with metallic
copper, which will then by reason of greater affinity unite with
the aluminium, while the iron will retain but an insignificant
amount of it. On cooling the bath, the bronze and iron sepa-
rate in such a manner that they can readily be kept apart. In
place of pure aluminium fluoride, cryolite may advantageously
be employed, or aluminium chloride may also be used, in which
case silicon chloride volatilizes instead of the fluoride. Or
again, pure silicon may be used with aluminium fluoride, cryo-
lite, or aluminium chloride, in which case pure aluminium is
obtained."
Mr. W. P. Thompson* has taken out a patent in England|
for the manufacture of aluminium and similar metals, which is
carried out as follows : " The inventor employs as a reducing
agent iron, either alone or conjointly with carbon or hydrogen.
The operation is effected in an apparatus similar to a Bessemer
converter, divided into two compartments. In one of these
compartments is placed melted iron, or an alloy of iron, which
is made to run into the second by turning the converter. This
last compartment has two tuyeres, one of which serves to in-
troduce hydrogen, while by the other is introduced either alu-
minium chloride, fluoride, double chloride or double fluoride,
with sodium, in liquid or gaseous state. In the presence of the
hydrogen, the iron takes up chlorine or fluorine, chloride or
fluoride of iron is disengaged, and aluminium mixed with car-
bon remains as a residue. Then this mixture of iron, alumin-
ium and carbon is returned to the other compartment, where
the carbon is burnt out by means of a current of air. The
mass being then returned to the chamber of reduction, the
operation described is repeated. When almost all the iron has
been consumed, the reduction is terminated by hydrogen alone.
There is thus obtained an alloy of iron and aluminium. (The
preparation of sodium does not require the intervention of
hydrogen. A mixture of iron with an excess of carbon and
* Bull, de la Soc. Chem. de Paris, 1880, xxiv. 719.
t March 27, 1879, No. 2101.
420 ALUMINIUM.
caustic soda (NaOH) is heated in the converter, when the so-
dium distils off. When all the carbon has been burnt, the iron
remaining as a residue may be converted into Bessemer steel.
As iron forms an alloy with potassium, the method would
scarcely serve for the production of that metal.) To obtain
the pure aluminium, sodium is first prepared by the process in-
dicated, the chloride or fluoride of aluminium is introduced into
the apparatus in the other chamber, when the metal is reduced
by the vapor of sodium. The chambers ought to be slightly
inclined, and an agitator favors the reaction. The inventor
intends to apply his process to the manufacture of magnesium,
strontium, calcium and barium."
That aluminium could be produced at all by the above re-
actions is very improbable ; it is not likely that the reactions
were even seriously tested.
Calvert and Johnson * made experiments on the reduction
of aluminium by iron, and the production thereby of iron-
aluminium alloys. We give the report in their own words: —
"We shall not describe all the fruitless efforts we made, but
confine ourselves only to those which gave satisfactory results.
The first alloy we obtained was by heating to a white heat for
two hours the following mixture : —
8 equivalents of aluminium chloride 1076 parts.
40 " iron filings 1 120 "
8 " lime 224 "
"The lime was added to the mixture with the view of remov-.
ing the chlorine from the aluminium chloride, so as to liberate
the metal and form fusible calcium chloride, CaClj. Subtract-
ing the lime from the above proportion, we ought to have
obtained an alloy having the composition of i equivalent of
aluminium to 5 equivalents of iron, or with 9.09 per cent, of
aluminium. The alloy we obtained contained 12 per cent.,
which leads to the formula AlFe^. This alloy, it will be noticed,
has an analogous composition to the one we made of iron and
*Phil. Mag., 1855, A. 240.
REDUCTION OF ALUMINIUM COMPOUNDS. 42 1
potassium, and like it was extremely hard, and rusted when
exposed to a damp atmosphere. Still it could be forged and
welded. We obtained a similar alloy by adding to the above
mixture some very finely pulverized charcoal and subjecting it
to a high heat in a forge furnace for two hours. This alloy
gave on analysis 12.09 per cent.* But, in the mass of calcium
chloride and carbon remaining in the crucible there was a large
amount of globules varying in size from a pin-head to a pea,
as white as silver and extremely hard, which did not rust in
the air or in hyponitric fumes. Its analysis gave 24.55 P^""
cent, aluminium ; the formula AljFej would give 25 percent.
Therefore this alloy has an analogous composition to alumina,
iron ifeplacing oxygen. We treated these globules with weak
sulphuric acid, which removed the iron and left the aluminium,
the globules retaining their form, and the metal thus obtained
had all the properties of the pure aluminium.
"We have made trials with the following mixtures, but al-
though they have yielded results, still they are not sufiSciently
satisfactory to describe in this paper, which is the first of a
series we intend publishing on alloys. This mixture was: —
Kaolin 1 750 parts.
Sodium chloride 1 200 "
Iron 87s "
"From this we obtained a metallic mass and a few globules
which we have not yet analyzed."
(See also Benzon's process, p. 414.)
M. Chenot,t on the occasion of Deville's first paper on alu-
minium being read to the French Academy, Feb. 6, 1854, an-
nounced that in 1847, by reducing earthy oxides by means of
metallic sponges, he had obtained a series of alloys containing
up to 40 per cent, of the earth metals. He cited from a
* In the original paper it is given as 1 2.09 per cent. iron. The inference is un-
avoidable that this was a misprint, but it is not corrected in the Errata at the end of
the volume.
tComptes Rendus, xxxviii^4i5.
422 ALUMINIUM.
memoir presented by him to the " Societe d'Encouragement,"
in 1849, in which he had said, "on taking precipitates of the
earths, they are all reduced by the metallic sponge {e. g., that
formed by reducing iron oxide in a current of carbonic oxide
gas). In this manner I have made barides, silicides, aluminides,
etc., all of which are beautiful silver-white, very hard and un-
oxidizable in air or in contact with acid vapors. They are
fusible, can be cast, and work perfectly under the hammer."
Faraday and Stodart* made an exhaustive investigation on
the preparation of iron-aluminium alloys, being started on this
line by finding that Bombay " wootz" steel contained O.O128 to
0.0695 psi" cent, of aluminium, while no metals of the earths
were to be found in the best English steels. This led to the
conclusion that the peculiar properties of the former, especially
the " damasceening," were due to the small amount of alumin-
ium. These scientists commenced by taking pure steel or
sometimes good soft iron and intensely heating it for a long
time imbedded in charcoal powder. Carbides were thus
formed, having a very dark gray color, and highly crystalline.
Average analysis of this product gave 5.64 per cent, carbon.
This was broken and powdered in a mortar, mixed intimately
with pure alumina, and heated in a closed crucible for a long
time at a high temperature. An alloy was obtained of a white
color, close granular texture and very brittle, containing 3.41
per cent, of aluminium, with some carbon.
When 40 parts of this alloy were melted with 700 parts of
good steel (introducing O.184 per cent, of aluminium) a malle-
able button was obtained which gave a beautiful damask on
treatment with acids ; while 6"] parts of the alloy with 500 of
steel (introducing 0.4 per cent of aluminium) gave a product
which forged well, gave the damask and " had all the appreci-
able characters of the best Bombay wootz." This appears to
be very strong synthetic evidence that alumina is reduced to a
small extent even in the rude hearths in which the Indian steel
is manufactured. Karsten, however, could not find weighable
* Quarterly Journal, ix. 320.
REDUCTION OF ALUMINIUM COMPOUNDS. 423
quantities of aluminium in specimens of wootz, nor could
Henry, a very expert analyst. The latter suggested that Fara-
day was misled by the alumina contained in intermingled slag,
yet the latter obtained alumina without silica in his analyses.
In the light of more recent developments we would accept
Faraday's results as being very near the truth in the matter.
Ledebuhr* quotes an analysis made by Griiner in which 0.50
per cent, of aluminium was found in cast-iron containing be-
sides 2.30 per cent, of carbon and 2.26 per cent, of silicon.
This would tend to show that under certain conditions iron
takes up aluminium in the blast-furnace. Karsten, however, in
his many analyses of malleable iron, steel and cast-iron, only
found aluminium in unweighable quantities. Griiner and Lauf
stated that aluminium is reduced in small quantities in the blast
furnace if the temperature is high and the slag basic; a large
addition of lime thus increases the reduction of alumina and
hinders that of silica. Most pig irons contain very small
amounts of aluminium, but some English varieties contain 0.5 to
i.o per cent, and several Swedish pig irons 0.75 per cent.
Schafhautl:j: found as much as i.oi per cent of aluminium in a
gray iron, and was led to consider silicide of iron and aluminide
of iron as characteristic components of gray iron. Lohage§
states that adding alumina in the manufacture of cast-steel has
a great influence on the grain and lustre of the steel, the effect
being doubtless due to a minute quantity of aluminium taken
up. Silicates of magnesium and aluminium are formed at the
same time, and separating out, float on the surface of the molten
steel. Corbinjl reports 2.38 per cent, of aluminium in chrome
steel ; but Blair,ir of Philadelphia, found no more aluminium in
chrome than in other steels. This chemist has examined many
* Handbuch der Eisenhiittenkunde, p. 265.
t Berg u. Hiittenmannische Zeitung, 1862, p. 254.
X Erdman's Journal fr. Pr. Chemie, Ixvii. 257.
§ Berg u. Huttenmannische Zeitung, 1861, p. 160.
II Silliman's Journal, 1869, p. 348.
t H. M. Howe, E. and M. J., Oct. 29, 1887.
424 ALUMINIUM.
irons and steels particularly for aluminium, and reports that
nearly always it exists as such in steel, but never more than a
few thousandths of i per cent., say 0.032 per cent as a maxi-
mum. He has further been unable to connect its presence
with any peculiarity in the properties of the metal or its mode
of manufacture.
G. H. Bilhngs,* of the Norway Iron Works, Boston, made
the following experiment on reducing alumina in contact with
iron : — A soft iron was used containing a trace of sulphur and
phosphorus, no manganese and only 0.08 per cent, of carbon.
The mixture was made of
12 parts emery.
18 " alumina.
I " pulverized charcoal.
36 " fine iron turnings.
These were mixed thoroughly, and heated to whiteness for 48
hours. The melting resulting showed a solid, homogeneous
fracture with a fine crystalline structure resembling steel with i
per cent, of carbon, and contained on analysis
0.20 per cent, of carbon.
0.50 " aluminium.
It was also found that if this quantity of aluminium was added
to a pot of molten iron, the product obtained exhibited the same
characteristics as the above.
Another attempt to produce iron-aluminium alloys directly
is stated in E. Cleaver's patent specifications as follows : f
Four parts of aluminium sulphate in solution are mixed with
one part of lamp-black, the mixture dried and heated to the
highest temperature attainable by using coal-gas and oxygen
in a lime-lined furnace similar to those used for melting plati-
num. Excess of reducing gas is maintained. The charge is
cooled in the furnace, removed, mixed with twenty-times its
weight of finely-divided cast-iron, and fused in a steel melting
* Transactions American Inst. Mining Engineers, 1877, p. 452.
t English Patent, 1276, Jan. 26, 1887.
REDUCTION OF ALUMINIUM COMPOUNDS. 425
furnace. If copper is used, a bronze results. The alloying
metal may be added in the gas furnace, but this is not recom-
mended as economical. This inventor also claims that alu-
minium ferrocyanide, either alone or with carbon, can be
decomposed in the above-described gas furnace, yielding a rich
iron-aluminium alloy. As a higher heat than before is needed,
it is recommended that the oxygen be previously heated. The
principal difficulty in this latter process would apparently be to
procure the aluminium ferrocyanide to operate on.
Mr. Ostberg,* connected with the Mitis process for making
wrought-iron castings, stated that the ferro-aluminium used in
that process in Sweden was made by adding clays to iron in
process of smelting, that it contained 7 to 8 per cent, of alu-
minium, and could be made very cheaply. Inquiries made for
further particulars about this process have received no satisfac-
tory reply, and there is no outside confirmation of the above
statement to be found.
Brin Bros, claim that they can alloy aluminium in small
quantities with iron (see p. 417). Besides the processes de-
scribed as most suitable for producing bronze, they also state
that if soft strap-iron is coated with the flux composed of clay
and salt and heated to over 1000° C. in a mufHe or a blowpipe
flame, the iron absorbs aluminium and becomes tough and
springy, having many of the properties of steel. They also
claim that by simply charging broken lumps of cast-iron into
a cupola with alternate layers of common clay and a flux, the
metal run down contains as much as 1.75 per cent, of alumin-
ium, yielding a very fluid, strong iron, which runs into the
thinnest castings. The London papers state that the alloys
thus produced assuredly contain aluminium, and that the con-
tained aluminium does not cost over 25 cents per lb.
A newspaper report speaks of exactly similar processes be-
ing operated by an aluminium company in Kentucky. (See
also p. 403.) It is said that they charge a cupola with scrap-
iron, pig-iron, coke, clay, and a flux,- and that on melting the
* Engineering and Mining Journal, May 15, 1886.
426 ALUMINIUM.
charge down and pouring, the castings produced are similar to
the best steel, the fracture of the metal being white, slightly-
fibrous, and free from blow-holes. It is stated, further, that the
castings, on analysis, contained 1.7 per cent, of aluminium.
Scrap-iron is also treated in the same way as reported by Brin
Bros., being simply coated with a pasty mixture of clay and a
flux and heated almost white-hot, when the iron absorbs alu-
minium.
The Aluminium Process Company of Washington, D. C,
own several patents granted to W. A. Baldwin, of Chicago, 111.
In one of these,* a bath is formed by fusing together 4 parts of
ground clay, 12 parts of common salt and i part of charcoal
powder. The metal to be alloyed, e. g., an iron bar, is thrust
into the bath, which is not hot enough to melt it, and allowed
to remain some time, with occasional stirring, until the alloying
is complete. In the case of metals with low fusing points the
metal may be melted with the mixture. It is claimed that the
metal takes up a small percentage of aluminium. With a more
highly aluminous material than clay, the proportions of salt and
carbon are to be increased proportionately. In a modification
of this process adopted for foundry practice,! a mixture of clay,
salt and carbon, similar to the above, is put into a large ladle
and the molten iron tapped directly from the cupola on to it.
A brisk stirring up of the iron takes place, much scum rises to
the surface, and the resulting iron is more fluid, can be carried
further before setting, and makes sounder and stronger castings
than similar iron not treated. The resulting iron does not
contain enough aluminium to be detected by quantitative
analysis. Old-fashioned fluxes used long ago in foundries were
similar in composition to this mixture used by Baldwin, and
were found efficacious in freeing dirty iron from slag and other
impurities. It is hard to see how this latter process is anything
but the use of a common flux, with a different explanation as
to how it acts — the explanation being probably the most ques-
* English Patent, 2584, Feb. 21, 1888.
tU. S. Patent, 380161, March 27, 1888.
REDUCTION OF ALUMINIUM COMPOUNDS. 427
tionable part of the whole. The first-mentioned process, how-
ever, has the merit of novelty, and pieces of poor iron treated
by it are made springy and much like steel, but whether this is
due to absorption of aluminium is doubtful.
The Williams Aluminium Company, of New York City
(works at Newark, N. J.), manufacture an alloy which they call
aluminium-ferro-silicon and sell for foundry use. When first
introduced, this alloy was represented to contain 10 per cent, of
aluminium, but several analyses disproved this, and afterwards
the alloy was sold simply on the guarantee of what it would
accomplish. The metal since sold by this company does
contain a small amount of aluminium, and its action on poor
foundry iron is similar to that of other brands of ferro-alumin-
ium ; therefore, as long as no certain percentage of aluminium
is now claimed, the company is certainly doing a legitimate
business. (For method of using, etc., see Chap. XVI.) The
alloy is made by melting down a mixture of iron filings, clay,
salt,' charcoal, and another flux whose composition is not
divulged. This is put into cast-iron pots and the whole charge,
crucibles and all, run down in a furnace of peculiar design
constructed by Mr. Williams. The capacity of the plant is
about 1000 lbs. of alloy a day, which is broken by small stamps
into pieces of about an inch diameter and sold at 10 cents
per lb. Mr. Williams also experimented on manufactur-
ing aluminium bronze by the same methods, and a sample
piece forwarded the author contained a small percentage of
aluminium.
G. Bamberg, London,* claims to produce alloys of alumin-
ium by taking iron or copper rich in silicon, putting them
molten into a Bessemer converter, raising the temperature by
blowing air through in the usual way, and then passing in
vapors of aluminium chloride or aluminium-sodium double
chloride.
Mr. Chas. T. Holbrook, connected with the well-known
* English Patent, 7666, May 8, 1889.
428 ALUMINIUM.
iron-masters Marshall Brothers, of Philadelphia, has reported
the existence of aluminium in the pig-iron made at the Marshall
furnace, Newport, Perry county. Pa. Mr. Holbrook has made
many tests on the efTect of adding aluminium to cast-iron, and
on one occasion, happening to see pig-iron being tapped from
this furnace, he remarked that it flowed as if it contained alu-
minium, judging by its bright, silvery appearance. An analy-
sis of the pig-iron was at once made, and confirmed this opin-
ion by showing 0.267 per cent. Since then, numerous analyses
have shown an average of 0.20 to 0.50 per cent., while for a
short period, when the furnace was working much hotter than
usual, over one per cent, has been obtained. The question as
to what circumstances favor this considerable reduction of alu-
mina is probably to be referred to the nature of the combina-
tion in which it occurs in the ores. It is found, for instance,
that when using ores from the Juniata Valley, the iron was
richer in aluminium than when a larger amount of ore from a
distance was used. The composition of the local ores is there-
fore of interest, and the following are copied from a letter of
Mr. Holbrook's : *
Grafton Fossil Ore. Juniata Hematite
(Dried at ioo° C.) (Dried at ioo° C.)
Silica 10.680 17.580
Alumina 12.469 5-692
Ferric oxide 73.481 6l-l33
Manganese oxide 0.431 0.700
Fhosphoric acid i .1 70 0.895
Sulphuric acid none none
Lime trace trace
Magnesia none none
Combined water and organic matter 2.700 10.700
100.931 96.700
The pig-iron made contains 3 to 5 per cent of silicon, and is
a first-class foundry iron.
Most aluminium was reduced when using the Grafton ore,
and it appears in this ore the alumina is present in a much
* Iron Age, June II, 1891.
REDUCTION OF ALUMINIUM COMPOUNDS. 429
larger proportion than it could be if combined with silica alone.
In other words, if the siKca were all present as ordinary clay,
it could not be combined with over 9 per cent, of alumina. It
is to me a very probable conclusion that the ore either con-
tains free alumina, or possibly, some Hercynite, the aluminate of
iron, FeO.AljOs. This compound would evidently reduce to an
iron-aluminium alloy. Whatever be the real reason for it, the
fact remains that this is a real instance of aluminium being re-
duced from alumina in the presence of iron, at the temperature
of a blast furnace of moderate size. This temperature prob-
ably never exceeds 2000° C.
Pearson and Pratt* have patented the following means for
facilitating the reduction of aluminium in the iron blast-fur-
nace. Calcined iron ore is mixed with a considerable quantity
of clay and the necessary amount of coke, and charged into a
blast-furnace with fluorspar for a flux instead of limestone.
Cast-iron containing aluminium results.
Reduction by or in Presence of Zinc.
M. Beketoff,! was not able to reduce vapor of aluminium
chloride by vapor of zinc, although silicon chloride under the
same conditions was readily reduced.
M. Dullo| observes that the double chloride of aluminium
and sodium, which he makes directly from clay, may be re-
duced by zinc. He says, " The reduction by zinc presents no
difificulties, but it is less easy than with sodium. An excess
of zinc should be employed, which may be got rid of after-
wards by distillation. The, metal thus prepared possesses all
the characteristics and all the properties of that obtained from
bauxite with sodium."
M. N. Basset,§ a chemist in Paris, patented a somewhat sim-
* English Patent, 18048, Nov. 12, 1889.
t Bulletin de la Societe Chemique, 1857, p. 22.
J Bull, de la Soc. Chem., i860, v, 472.
§Le Genie Industriel, 1862, p. 152.
430 ALUMINIUM.
ilar process for obtaining aluminium. If the statements are
correct they are of great value. The paper is as follows :
" All the metalloids and the metals which form by double de-
composition proto-chlorides or sesqui-chlorides more fusible or
more soluble than aluminium chloride may reduce it or even
aluminium-sodium chloride. Thus, arsenic, bismuth, copper,
zinc, antimony, mercury, or even tin or amalgam of zinc, tin,
or antimony may be employed to reduce the single or double
chloride. The author employs zinc in preference to the others
in consequence of its low price, the facility of its employment,
its volatility, and the property which it has of metallizing easily
the aluminium as it is set free. When metallic zinc is put in
the presence of aluminium-sodium chloride, at 250° C. to 300°
C, zinc chloride, ZnCl^, is formed and aluminium is set free.
This dissolves in the zinc present in excess, the zinc chloride
combines with the sodium chloride, and the mass becomes lit-
tle by little pasty, then solid, while the alloy remains fluid. If
the heat is now raised, the mass melts anew, the zinc reduces a
new portion of the double chloride and the excess of zinc en-
riches itself in aluminium proportionately. These facts consti-
tute the basis of the following general process : One equiva-
lent of aluminium chloride is melted, two of sodium chloride
added, and when the vapors of hydrochloric acid are dissipated,
four equivalents of zinc, in powder or grain, are introduced.
The zinc melts rapidly, and by agitation the mass of chloride
thickens and solidifies. The mass is now composed of the
chlorides of aluminium, zinc and sodium, and remains in a
pasty condition on top of the fluid zinc containing aluminium.
This pasty mass is removed, piled up in a crucible or in a fur-
nace, and bars of the fluid alloy of zinc and aluminium ob-
tained from a previous operation are placed on top of it. This
is gradually heated to bright redness, and kept there for an
hour. The melted mass is then stirred with a rake and poured
out. It is an alloy of the two metals in pretty nearly equal
proportions. This alloy, melted with some chloride from the
first operation, furnishes aluminium containing only a small
REDUCTION OF ALUMINIUM COMPOUNDS. 43 1
per cent, of zinc, which disappears by a new fusion under alu-
minium chloride mixed with a little fluoride, providing the
temperature is raised to a white heat and maintained till the
cessation of the vapors of zinc, air being excluded.
" The metal is pure if the zinc employed contained no foreign
materials or metals. In case the zinc contains iron, or even if
the aluminium chloride contains some, the metallic product of
the second operation may be treated with dilute sulphuric acid
to remove it. The insoluble residue is washed and melted
layer by layer with fluorspar or cryolite and a small quantity of
aluminium-sodium chloride, intended solely to help the fusion."
Mr. Wedding,* makes the following remarks on this process :
" It is some time since Mr. Basset established the possibility
of replacing sodium by zinc in the manufacture of aluminium.
Operating on aluminium-sodium chloride with granulated zinc,
the reduction takes place towards 300°. The reduced alumin-
ium dissolves in the excess of zinc, while the zinc chloride
formed combines with the sodium chloride, forming a pasty
mass if the heat is not raised. Under the action of heat the
alloy enriches itself in aluminium, because the zinc volatilizes.
The zinc retained by this alloy is completely eliminated by fus-
ion with double chloride and a little fluorspar. The tempera-
ture ought' to be pushed at least to a white heat, and main-
tained till no vapor of zinc escapes, air being excluded during
the operation. These results I have confirmed, having sub-
mitted the experiments of Mr. Basset to an attentive examina-
tion, and I recommend its use. However, the process de-
mands very much precaution, because of the high temperature
which it necessitates. Another chemist, Mr. Specht, even in
i860 decomposed aluminium chloride by zinc, and has the
same report to make — that he thinks the process will be some-
time advantageously practised on a large scale."
The author made the following experiment to determine if
cryolite would be reduced by zinc : One pound of finely pow-
* Journal de Pharm. [4] iii. p. 155 (1866.)
432 ALUMINIUM.
dered cryolite was melted in a graphite crucible, and 6 ounces
of granulated zinc dropped into it. No perceptible reaction
took place except the volatilization of zinc when the crucible
was uncovered, and the metal obtained after 15 minutes' treat-
ment contained on analysis 0.6 per cent, of aluminium.
Mr. Fred J. Seymour * patented the reduction of aluminium
by zinc, making the following claim : An improvement in ex-
tracting aluminium from aluminous earths and ores by mixing
them with an ore of zinc, carboniferous material and a flux,
and subjecting the mixture to heat in a closed resort, whereby
the zinc is liberated, is caused to assist in bringing or casting
down the aluminium in a metallic state, and the alloy of alu-
minium and zinc is obtained.
A furnace was put up in the early part of 1884, somewhere
in the vicinity of Cleveland, in a description of which by a
newspaper correspondent we are told that steel retorts were
charged with a mixture of zinc ore 100 parts, kaolin 50, carbon
(either anthracite coal or its equivalent of some hydrocarbon)
125, pearlash 15, common salt 10: the heat necessary being
about 1400° C. In a second patent, f Mr. Seymour claimed
that by heating the same mixture in a retort and introducing
air he volatilized oxides of aluminium and zinc, which were
caught in a condenser, mixed with carbon, and reduced in a
crucible. Immediately after the issue of this patent, the Amer-
ican Aluminium Company was organized in Detroit with a cap*-
ital stock of $2,500,000 to operate the patents of a Dr. Smith,
under whose name processes similar to the above had been
patented in Great Britain and France. A works was then
started at Findlay, Ohio, using natural gas for fuel. A gentle-
man who saw the plant described it as a reverberatory furnace
into which a charge of 800 lbs. of zinc ore, 900 of native alum,
and 300 of charcoal was put. On heating very strongly by gas
with plenty of air admitted, zinc oxide was volatilized (Mr. Sey-
*U. S. Pat., No. 291631, Jan. 8, 1884.
tU: S. Patent, 337,996, March 16, 1886.
REDUCTION OF ALUMINIUM COMPOUNDS. 433
mour claimed that it carried alumina with it), and was con-
densed by passing the gases through large copper condensers.
This fume was then collected, mixed with carbon and a metal,
and run down in a crucible to an alloy. It was clairiied that
the plant had a capacity of 600 lbs. of pure aluminium a day,
and had presumably been in operation over a year, yet there
was not over 20 lbs. of alloys or j^ lb. of pure aluminium to
show for it. On closer inspection so plain indications of fraud
were visible in the last part of the operation that, although ver-
itable aluminium alloys were taken out of the crucible, the gen-
tlemen referred to refused to believe that the aluminium was
produced in the process. As the sequel to this it can be
stated that in the middle of 1889 the executive committee for
the stockholders, being fully satisfied of the worthlessness of
the process, called for a meeting to wind up the company.
One month later Mr. Seymour died. The story went the
rounds of the daily press that the one metallurgist who com-
manded the secret of obtaining cheap aluminium had died, tak-
ing the talisman with him, and a vivid picture was drawn of the
manner in which the secret had been preserved by means of
twelve-foot palisades, double-bolted doors, and by working at
the midnight hour. Alas, the secret was out one month before
he died !
A method of reducing cyanide of aluminium by means of
zinc is the subject of a patent granted F. Lauterborn.* Four-
teen parts of aluminium sulphate dissolved in twice its weight
of water is precipitated by thirteen parts of ferro-cyanide of
potassium dissolved in four times its weight of water ; the pre-
cipitate of ferro-cyanide of aluminium is collected and dried.
This substance is then mixed with slightly less than one-half its
weight of dry, anhydrous sodium carbonate, put in a crucible
and ignited with as little admission of air as possible. The
ferro-cryanide is decomposed, iron carbide separates out, and
besides sodium cyanate, the double cyanide of aluminium and
* German Patent, 39915 (1887),
28
434 ALUMINIUM.
sodium (Al2Cy6+3NaCy) is obtained as a melted mass which
is poured away from the heavier iron carbide at the bottom of
the crucible. If two parts of this salt are then ignited with one
part of zinc in a covered crucible, aluminium separates as a
regulus, while double cyanide of sodium and zinc remains as
slag. The slag is dissolved in water and treated with metallic
iron, whereby metallic zinc is precipitated out and a solution of
ferro-cyanide of soda remains and can be used over in the pro-
cess.
I do not know whether Lauterborn has ever succeeded in
carrying out this process ; it would appear at the very begin-
ning that the precipitation of aluminium ferro-cyanide, although
appearing a priori possible, has always been found impractic-
able, alumina being precipitated.
J. Clark, of Birmingham, England, has taken out several pat-
ents in England and one in Germany. In the first,* hydrated
aluminium chloride is to be mixed with lime, iron, zinc, am-
monia, or any other substance which combines readily with
chlorine, and finely divided coke. After drying the mixture it
is introduced into the iron blast furnace or blown into the Bes-
semer converter, an iron-aluminium alloy being thus produced.
In a second patent,! hydrated aluminium chloride is to be
mixed with 2 ^2 parts of granulated zinc and i part of iron
turnings or borings, or the alloy of the zinc and iron known as
"zinc dross" might be used. The mass is let stand 24 hours
and dried. The orange-colored powder resulting is mixed
with borax (!) or any suitable flux, and put in a crucible with
20 parts of fine granulated copper and melted down. After
about an hour the zinc and iron present have probably volatil-
ized as chlorides, while aluminium bronze remains. When the
copper is to be alloyed in large quantities, it may be melted on
the hearth of a reverberatory furnace and the prepared powder
stirred into it.
* English Patent, 15946, Dec. 6, 1886.
t English Patent, 10594, Aug. 18, 1886; German Patent, 40205, (1887).
REDUCTION OF ALUMINIUM COMPOUNDS. 435
Dr. J. D. Lisle, of Springfield, Ohio, made the following ex-
periments in reducing aluminium sulphide by zinc. The sul-
phide was made in a crucible, mounted on trunnions to keep
the contents agitated, in which alumina was placed and treated
with superheated carbon bi-sulphide vapor. While the con-
tents were still hot, solid or melted zinc was put into it, the
heating continued, the crucible constantly agitated and a cur-
rent of hydrocarbon gas led into the crucible through a hole in
the cover. The outcoming gas contained some sulphuretted
hydrogen, seeming to show that reduction was accomplished
partially, at least, by the hydrocarbon. After heating about
half an hour the openings were sealed up and the apparatus
cooled. The product was analyzed, and the result of nine ex-
periments gave results varying from 1.06 to 10 per cent, of
aluminium present in the zinc. The richest alloy was distilled
carefully, leaving aluminium which analyzed 98 per cent, pure
and contained only a trace of zinc. It is difficult, however, to
see any possibility of a commerical process being worked up
on these lines which could compete with the present methods
of extraction.
G. Bamberg, of London,* claims that if metallic zinc is vapor-
ized it will reduce the vapor of aluminium chloride. He puts
metallic zinc in a retort heated sufficiently to distil off zinc
vapor, and in another retort is placed aluminium chloride or
aluminium-sodium chloride. The vapors mix in a third highly
heated chamber, in which they react, and there is condensed an
alloy rich in aluminium. This is heated to whiteness in an-
other retort to distil off the zinc.
Reduction by Lead.
According to the invention of Mr. A. E. Wilde, f of Notting
Hill, lead or sulphide of lead, or a mixture of the two, is melted,
and in a molten state poured upon dried or burnt alum. The
* English Patent, 7667, May 8, 1889.
t Sci. Am. Suppl., Aug. 11, 1887.
436 ALUMINIUM.
crucible in which the mass is contained is then placed in a fur-
nace and heated, with suitable fluxes. The metal, when poured
out of the crucible, will be found to contain aluminium. The
aluminium and lead can be subsequently separated from each
other by any known means, or the alloy or mixture of the two
metals can be employed for the various useful purposes for
which lead alone is more or less unsuited.
Reduction by Manganese.
Walter Weldon * claimed to melt together cryolite with cal-
cium chloride or some other non-metallic chloride or sulphide,
and then to reduce the aluminium chloride or sulphide pro-
duced by manganese, also adding metallic sodium to promote
the reaction. Of course, the manganese would be used as ferro-
manganese or spiegeleisen, and an iron alloy produced. Dr.
Green, of Philadelphia, mixed powdered spiegeleisen with cryo-
lite, placed the mixture in a graphite crucible, and heated it
close to the ports of an open-hearth steel furnace until it soft-
ened, yet the iron contained afterwards only 0.3 per cent, of
aluminium.
When we examine closely the heat of combination of man-
ganese and aluminium compounds (Chapter VIII.) we see that
in the combinations with chlorine and sulphur manganese is
the stronger element, and we should therefore be led to expect
that manganese would reduce aluminium chloride or sulphide.
On the other hand, in the oxides, and particularly in the flu-
orides, aluminium is the stronger element. We should there-
fore expect aluminium to reduce manganese oxide and fluoride.
This is, in fact, just what occurs. Drs. Green and Wahl, of
Philadelphia, are, in fact, producing pure manganese on a com-
mercial scale by dissolving manganese oxide in melted cryolite
and adding metallic aluminium, f
* English Patent, No. 97 (1883).
t See Journal of the Franklin Institute, March, 1893, P- 218.
reduction of aluminium compounds. 437
Reduction by Magnesium.
Magnesium develops more heat in forming compounds than
aluminium does (see p. 229), which would indicate that it
would reduce aluminium compounds easily. Only one or two
statements on this point can be found. Margottet * states that
magnesium will decompose molten cryolite, setting the alu-
minium at liberty. R. Gratzel f patents the reduction of a
double fluoride of aluminium and potassium or sodium by
metallic magnesium, or by conducting magnesium vapor into
the liquid compound.
Roussin I states that magnesium does not precipitate alu-
minium in a metallic state from its solutions. To test this
point I placed a strip of magnesium in solution of aluminium
sulphate, when magnesium sulphate went into solution and a
precipitate of alumina was formed. It is apparent that the
aluminium is first precipitated in the metallic state and promptly
oxidized by the water as fast as set free, in a manner strictly
analogous to the production of alumina at the negative pole
when electrolyzing aqueous aluminium solutions.
In a patent awarded Count R. de Montgelas, of Philadel-
phia,§ it is stated that aluminium chloride is mixed with litharge,
charcoal and common salt ; fused and crushed. It is then re-
melted with magnesium filings and potassium chloride. After
cooling it is again crushed, mixed with more potassium chloride
and nitrate of potash, fused, poured into water, and the globules
of aluminium separated out.
Clemens Winkler || states that when alumina is heated with
powdered magnesium, in a current of hydrogen gas, it gives a
nearly black powder containing over 40 per cent, of a sub-oxide
of aluminium to which he assigns the formula AlO, together
* Fremy's Ency. Chim.
t English Patent, 14325, Nov. 25, 1885.
{ Jrnl. de Pharm. et de Chimie, iii., 413.
§ English Patent, 10606, August 18, 1886.
II Berliner Berichte, xxiii. p. 772.
438 ALUMINIUM.
with magnesium oxide and unaltered alumina. The last two
are partly combined to magnesium aluminate. No metallic
aluminium was obtained.
Reduction by Antimony.
F. Lauterborn * proposes to decompose aluminium sulphide
by means of antimony and carbon. One hundred parts of
dried aluminium sulphate is mixed with 50 parts of charcoal
and 72 parts of metallic antimony ; some sodium carbonate and
fluorspar is then added, and the mixture melted. It is claimed
that antimony sulphide and aluminium are found in the pro-
duct, the former being in the bottom of the crucible. In a
modification of this process it is claimed t that if a mixture of
dried aluminium sulphate, sodium carbonate, and antimony
sulphide (stibnite) is put into a shaft filled with incandescent
coke, antimony will be first set free by the reaction
2Sb2S3+6Na2C03+3C=6Na,S+9CO,+4Sb,
and that these products act further on the aluminium sulphate,
setting free aluminium by the reaction
2 Al, (SO*) 3+ 6Na,S+4Sb+ 1 2C=4Na2SbS3f4Al-|- 1 2CO,.
The sodium sulph-antimonide can be smelted over with soda
and antimony regained.
These extraordinary formulas have little or no basis in chem-
ical science. Dr. Fischer J says plainly that they are false.
The author tried by direct experiment to reduce aluminium
sulphide by antimony, fusing down a mixture of powdered
antimony with aluminium sulphide, but the button of metal
obtained did not contain a trace of aluminium.
* German Patent, 32126(1885).
t Dingier, 256, 226 and 233.
I Wagner's Jahresbericht, 1885.
reduction of aluminium compounds. 439
Reduction by Tin.
J. S. Howard and F. M. Hill, assignors to the Aluminium
Product Company, of New York, make the following statements
in their patent specifications:* "Some aluminous material is
boiled in muriatic acid, cooled, mixed with Spianish white or
lime, the free acid evaporated off at a high temperature, and
the heat finally increased to about 1000° F., thereby volatiliz-
ing any iron present as chloride. The product thus obtained
is put into a lime-lined crucible along with lime, charcoal, fluor-
spar, cryolite and potassium bisulphate, the whole covered with
chloride of tin, and finally by common salt. This is subjected
to a smelting temperature, when on cooling it is claimed that
an alloy of tin and aluminium is obtained. To separate the
aluminium the alloy is melted with lead or bismuth, which alloy
with the tin, letting the aluminium float on the surface along
with oxides and other impurities. This is skimmed off and
purified by exposure to heat on a bed of porous material."
While we cannot altogether deny the possibility of metallic
tin reducing aluminium chloride, yet it is not at all probable
that this salt remains after the first ignition. It is also improb-
able that tin would reduce cryolite in the latter operation, but
there is no direct evidence to contradict the above statement.
In an experiment made by the author, aluminium sulphide
was heated with tinfoil for a short time at a red heat. The
resulting metal contained 0.52 per cent, of aluminium, and from
the proportions of tin and sulphide used, it was evident that a
large part of the aluminium sulphide present had been reduced.
Dr. J. D. Lisle, of Springfield, Ohio, has made experiments
of the same nature on a more extensive scale. Aluminium
sulphide was put in a crucible placed on trunnions, so as to
permit agitating the contents, and metallic tin in flakes was put
in with it. The crucible was closed, and when at a bright-red
heat a stream of super-heated gasoline vapor led into the cru-
* U. S. Patent, 378,136, Feb. 21, 1888.
440 ALUMINIUM.
cible. Hydrogen sulphide was copiously formed, but an ex-
plosion of gasoline vapor terminated the experiment. The
crucible was not broken, and when cool was opened. It con-
tained some shot-metal, which was collected and melted into a
button. This was the color of steel, very hard and tough, and
upon analysis gave 19.32 per cent, of aluminium. In another
experiment equal parts of aluminium sulphide and tin, in flakes,
were mixed together, placed in a graphite crucible, covered
with powdered charcoal, and kept at a red-heat for one-half
hour. The resulting button contained 9.8 per cent, of alu-
minium.
While such experiments are interesting as showing the pos-
sibility of tin reducing an aluminium compound, yet pure
aluminium cannot be made from the tin alloy, and metallic tin
is so costly a reducing agent, being worth about 1 5 cents per
pound, that this means of reduction can never be commercially
applied, since aluminium itself is selling so cheaply.
Reduction by Phosphorus.
L. Grabau * patented the following process, in 1883, but has
since virtually admitted that this method was not successful.
The proposition was as follows : A rich alloy of aluminium
and phosphorus is made by melting the two elements together
or by fusing aluminium with phosphor salts and a reducing
agent. The alloy is crushed, mixed with alumina or clay or
aluminous fluorides, covered with coal dust and heated to in-
candescence in a crucible. It was claimed that the phosphorus
combined with the oxygen or fluorine of the aluminous com-
pound, the metal produced uniting with the aluminium already
present. To produce any given alloy, the phosphide of the
required metal is substituted for the aluminium-phosphorus
alloy. Mr. Grabau broadens out his specifications into more
probable fields by adding that " manganesic or carburetted
metals may be used instead of the phosphide alloys, as reducing
* English Patent, 5798, Dec. 18, 1883.
REDUCTION OF ALUMINIUM COMPOUNDS. 44I
agents." It is almost needless to say that the generally small
heat of combination of phosphorus compounds would show
that the reactions proposed are in a high degree improbable.
Reduction by Silicon.
M. Wanner * makes the following general claims : The pro-
duction of aluminium by treating a fused bath of aluminium
fluoride or aluminous fluorides, while in a molten metallic bath
and protected from oxidizing agents, with a reagent whose
elements dissociate below the fusing point of the aluminium
fluoride or the aluminous fluorides, and having one element of
such affinity that it displaces the aluminium in the fluoride
compound, but having no element capable of combining with
the reduced aluminium. More specifically, sulphide of silicon
or an equivalent reagent is mentioned, and the reaction takes
place on the hearth of a short reverberatory furnace, the
metallic bath mentioned being preferably metallic iron or cop-
per, which are able to combine with the resulting aluminium.
The reaction proposed is so far out of the usual run of specu-
lations that no opinion can be hazarded as to its probability.
Further, silicon sulphide is an almost unknown compound, and
it would be very interesting to know how it is to be prepared ;
it would probably be a more difficult feat to get the reagent
alone than to produce aluminium by many well-known methods.
* U. S. Patent, 410568, Sept. 3, 1889.
CHAPTER XIII.
working in aluminium.
Melting Aluminium.
DevillE: "To melt aluminium it is necessary to use an
ordinary earthen crucible and no flux. Fluxes are always use-
less and almost always harmful. The extraordinary chemical
properties of the metal are the cause of this ; it attacks very
actively borax or glass with which one might cover it to pre-
vent its oxidation. Fortunately this oxidation does not take
place even at a high temperature. When its surface has been
skimmed of all impurities it does not tarnish. Aluminium is
very slow to melt, not only because its specific heat is consid-
erable, but its latent heat appears very large. It is best to
make a small fire and then wait patiently till it melts. One can
very well work with an uncovered crucible."
" In the fusion of impure aluminium very different phenomena
are observed, according to the nature of the foreign metal which
contaminates it. Ferruginous material often leaves a skeleton
less fusible and pretty rich in iron ; a liquation has taken plafte,
increasing the purity of the melted material. When the alu-
minium contains silicon this liquation is no longer possible, or
at least it is very difficult, and I have sometimes seen some
commercial aluminium so siliceous that the workmen were
unable to remelt it. When it is desired to melt pieces together
they can be united by agitating the crucible or compressing the
mass with a well-cleaned cylindrical bar of iron. Clippings,
filings, etc., are melted thus : Separate out first, as far as possi-
ble, foreign metals, and to avoid their combining with the alu-
minium heat the divided metal to as low a heat as possible, just
sufficient to melt it. The oil and organic matters will burn,
(442)
WORKING IN ALUMINIUM. 443
leaving a cinder, which hinders the reunion of the metal if one
does not pre§s firmly with the iron bar. The metal may then
be cast very easily, and there is found at the bottom of the
crucible a little cinder, which still contains a quantity of alu-
minium in globules. These may be easily separated by rubbing
in a mortar and then passing through a sieve, which retains the
flattened globules."
Biederman gives the following directions : " The whole quan-
tity of metal which is to be melted must not be put into the
crucible at once, but little by little, so increasing the mass from
time to time as the contents become fully melted. The neces-
sary knack for attaining a good clean melt consists in dipping
the pieces which are to be melted together in benzine before
putting in the crucible. Mourey even pours a small quantity
of benzine into the crucible after the full melting of the metal,
and he recommends the employment of benzine in the melting
of all the noble metals. To utilize the scrap pieces produced
in working aluminium into various useful articles, one must as
far as possible separate out first the pieces which have been
soldered, in order that the newly melted aluminium may not be
contaminated by the solder. The solder adhering to these
pieces can be removed by treating them with nitric acid, by
which the aluminium is not attacked."
Aluminium can be melted with perfect safety in common clay
or sand crucibles if they are lined with carbon. This can be
done by mixing lamp-black to a paste with molasses, plaster-
ing the inside of the crucible evenly and drying slowly for
several days at a moderate temperature. A means of getting a
more perfect lining is to ram the crucible full of this paste, dry-
ing slowly and then hollowing out a cavity of the required size
leaving a uniform lining of sufficient thickness. In using these
carbon-lined crucibles they should be kept well-covered, in
order that the carbon may not burn away too quickly, taking
particular care to place the cover on when the metal has been
poured out and the crucible is cooling in the air. Small
crucibles may be made of a single block of soapstone, and seem
444 ALUMINIUM.
to last a long while, the aluminium apparently having no action
on this mineral at a temperature a good deal higher than its
melting point.
With extra care, heating in a furnace where the heat is under
exact control, aluminium may be melted in sand crucibles or in
cast-iron ones. In using sand or Hessian crucibles no flux
must be added, and if the metal is heated slowly to a tempera-
ture only enough above its melting point to admit of pouring
quickly, it will be found that the crucible is unattacked. If,
however, the crucible is heated to a bright-red heat at any part,
it will be found that at that place the aluminium has attacked
the crucible, and on pouring out the metal a thin, tough skin
will be left adhering to the spot attacked and generally taking
with it bits of the wall when it is forcibly detached. This thin
sheet is hard, tough, and rich in silicon, while the rest of the
metal poured out has also absorbed a little silicon. An iron
crucible acts in precisely the same way ; if the heat is kept
close to the melting point of aluminium the latter does not
" wet" the iron, but at a bright- red heat it attacks it and ad-
heres, as in the case of the sarid crucible. I will repeat, that if
the temperature is kept as low as it is possible to melt and cast
the metal, and if no fluxes are used, neither the iron nor sand
crucibles are attacked.
In the large European works, where 500 or looo lbs. of alu-
minium are melted at once on the bed of a reverberatory fur-
nace, the hearth was formerly protected by pure bauxite,
closely rammed in and strongly fired before using, but basic
magnesia bricks have now been substituted, similar to those
used in basic open-hearth furnaces but of purer materials, and
they are reported as being all that can be desired in their capa-
city for resisting corrosion.
A very good lining for any kind of crucible is made by using
calcined magnesite, for which I recommend the white, Grecian
mineral, fully shrunk by calcining at the highest heat of a fire-
brick or porcelain kiln and then ground fine and made into a
stiff paste with sugar syrup or molasses. The crucible is care-
WORKING IN ALUMINIUM. 445
fully lined and then heated slowly to redness. On cooling, any
cracks are carefully filled with more paste, and the crucible is
baked again ; when properly prepared, however, one baking is
sufiScient, and the linings do not shrink from the walls of the
crucible. This lining is a very serviceable one, not only for
melting aluminium by itself, but also for using flux, for it re-
sists cryolite, fluorspar or even a siliceous slag perfectly. Since
experiment has shown that aluminium will take up about 0.25
per cent, of silicon from one re-melting at a red heat in a best-
quality graphite crucible, it is very important that such deteri-
oration be avoided if possible, and I earnestly advise all melt-
ers and casters of aluminium to take the trouble to prepare
these magnesite lined crucibles if they wish to get the best re-
sults. This magnesite can be procured from the importers of
chemicals in New York city, at a cost of about $0.02 per pound
for the burnt and ground material.
Casting Aluminium.
Deville: "Aluminium can be cast very easily in metallic
moulds, but better in sand for comphcated objects. The
mould ought to be very dry, made of a porous sand, and should
allow free exit to the air expelled by the metal, which is vis-
cous when melted. The number of vents ought to be very
large, and a long, perfectly round git should be provided.
The aluminium, heated to redness, ought to be poured rather
quickly, letting a little melted metal remain in the git till it is
full, to provide for the contraction of the metal as it solidifies.
In general, this precaution ought to be taken even when alu-
minium is cast in iron ingot moulds or moulds of any other
metal. The closed ingot moulds give the best metal for roll-
ing or hammering. By following these precautions, castings
of great beauty may be obtained, but it is not advisable to con-
ceal the fact that to be able to succeed completely in all these
various operations requires for aluminium, as for all other
metals, a special familiarity with the material which practice
alone is able to give."
446 ALUMINIUM.
The peculiarity of molten aluminium which a metal caster
would first notice is its viscousness, that is, it runs thick.
When about to pour, a thick edge or lip of metal forms, which
must in many cases be punctured in order to start the metal
flowing. On account of this property it does not run sharply
in the moulds except where a head of metal puts it under pres-
sure. To obtain sharp castings there must be a " gate" to give
pressure to the metal, and when we remember that the gravity
of aluminium is only 2.6 and that, besides, it does not flow
thinly, it will be seen that a much higher head of metal is
necessary to ensure sharp castings than is needed for iron,
brass, etc. A small slab of» aluminium two inches high run in
a closed iron mould with very little gate was quite sharp at the
lower end but had rounded corners at the top. For casting in
closed moulds, the best results as to sharp castings free from
cavities are obtained if a slight artificial pressure can be ap-
plied to the still liquid metal in the mould immediately after
pouring. This is accomplished by Dr. C. C. Carroll, of New
York, an expert in making cast-aluminium dental plates, by
closing in tightly the top of the crucible containing the molten
aluminium, and then by air pressure from a rubber bulb forcing
the metal through a syphon-shaped tube terminating under-
neath the metal and connecting tightly with the pouring gate of
the mould. The mould is previously heated, in order not to
chill the metal too quickly, and when the metal has been forcfed
out of the crucible by squeezing the bulb the pressure is con-
tinued for a short time in order to force the metal into every
crevice of the mould and allow the casting to set under pres-
sure.
The idea is undoubtedly correct, and the excellently sound
and extremely sharp castings obtained by Dr. Carroll attest its
success in practice.
The Passaic Art Casting Company, of Passaic, N. J., make
very fine castings in aluminium by the Smith pressure-casting
process, by which the finest details of engraved, chased or re-
poussee work are brought out with a finish equal to electro-
WORKING IN ALUMINIUM. 447
types. Moulds, either of sand or of a liquid plaster-of-paris
composition, are made in as flat a shape as possible so that they
may be piled on top of each other, the gates from each mould
leading to a central feeder. The entire charge of molten metal
is kept in a suitable holder above the moulds. The moulds
being air-tight, an air-pump is connected with the bottom of the
molds while pressure is put on the molten metal above. A
thin diaphragm used to keep the molten metal in the receiver
is burst by the pressure, allowing the aluminium to flow quickly
into the moulds, where it fills every minute cavity. Extremely
light and sharp castings, having remarkable solidity and free
from blow-holes, are thus obtained.
Aluminium can be cast in dry sand moulds, which are best
lined with powdered plumbago. The metal should be poured
fast, and not be far above its melting point, or the castings will
not be sound. The shrinkage to be allowed for is very nearly
one-quarter of an inch to the foot.
Quite recently a large amount of cast aluminium hollow-ware
has been made for culinary use. Tea-kettles have been cast in
one piece with walls only one-sixteenth of an inch thick. These
castings possess the advantage that they are more malleable
than any other cast metal. Thin castings of tea-kettles have
been hammered in and bent almost double before breaking,
Mr. W. S. Cooper, of Philadelphia, makes some remarkably
large sand-castings, adding a little copper to reduce the shrink-
age. Full-sized bath-tubs, 6 feet long, 2 feet wide, 2 feet deep,
and three-eighths inch thick, with a roll rim, and weighing com-
plete 140 lbs., are worthy of special mention, for such a cast-
ing would not be easy to make in the best-flowing metal.
Purification of Aluminium.
Freeing from slag. — Deville gives the following information
on this important subject :
" It is of great importance not to sell any aluminium except
that which is entirely free from the slag with which it was pro-
duced and with which its whole mass may become impregnated.
448 ALUMINIUM.
We have tried all sorts of ways of attaining this end, so as to ob-
tain a metal which would not give any fluorides or chlorides
upon boiling with water, or give a solution which would be pre-
cipitated by silver nitrate. At Glaciere we granulated the metal
by pouring it while in good fusion into water acidulated with
sulphuric acid ; this method partially succeeded. But the pro-
cess which M. Paul Morin uses at present (1859), and which
seems to give the best results, is yet simpler. Three or four
kilos of aluminium are melted in a plumbago crucible without
a lid, and kept a long time red-hot in contact with the air. Al-
most always acid fumes exhale from the surface, indicating the
decomposition by air or moisture of the saline matter impreg-
nating the metal. The crucible being withdrawn from the fire,
a skimmer is put into the metal. This skimmer is of cast iron ;
its surface ought not to be rough and it will not be wetted by
the aluminium in the least during the skimming; it may be of
advantage to oxidize its surface with nitre before using. The
white and slaggy matters are then removed, carrying' away also
a little metal, and are put aside to be remelted. So, in this
purification, there is really no loss of metal. After having
thus been skimmed, the aluminium is cast into ingots. This
operation is repeated three or four times until the metal is per-
fectly clean, which is, however, not easily told by its appearance ;
for, after the first fusion, the crude aluminium when cast into
ingots has a brilliancy and color such as one would judge quite
irreproachable, but the metal would not be clean when it was
worked, and especially when polished would present a multi-
tude of little points called technically ' piqiires,' which give to
its surface, especially with time, a disagreeable look. Alumin-
ium, pure and free from slag, improves in color on using. It
is the contrary with the impure metal or with aluminium not
free from slag. When aluminium is submitted to a slow, corrod-
ing action, its surface will cover itself uniformly with a white,
thin coating of alumina. However, any time that this layer is
black or the aluminium tarnishes, we may be sure that it con-
tains a foreign metal, and that the alteration is due to this im-
purity."
WORKING IN ALUMINIUM. 449
Freeing from impurities. — Again Deville is the authority, and
we quote his advice on the subject: —
" A particular characteristic of the metallurgy of aluminium
is that it is necessary, in order to get pure metal, to obtain it so
at the first attempt. When it contains silicon, I know of no
way to eliminate it: all the experiments which I have made on
the subject have had a negative result; simple fusion of the
metal in a crucible, permitting the separation by liquation of
metals more dense, seems rather to increase the amount of sil-
icon than to decrease it. When the aluminium contains iron
or copper, each fusion purifies it up to a certain limit, and if
the operation is done at a low heat there is found at the bottom
of the crucible a metallic skeleton containing much more iron
and copper than the primitive alloy. At first I made this liqua-
tion in the muffle of a cupel furnace, in which process the ac-
cess of air permitted the partial oxidation of these two metals.
The little lead which aluminium may sometimes take up may
thus be easily separated. Unfortunately, the process does not
give completely satisfactory results. It is the same in fusing
impure aluminium under a layer of potassium sulphide, KjSj;
there is a partial separation of the lead, copper, and iron. That
which has succeeded best with us is the process which we have
employed for a long time at Glaci^re, and which consists in
melting the aluminium under nitre in an iron crucible. We
have in this way improved the quality of large quantities of
aluminium. The operation is conducted as follows : Aluminium
has generally been melted with nitre in order to purify it by
means of the strong disengagement of oxygen at a red heat,
no doubts being entertained as to the certainty of the result.
But it is necessary to take great care when doing this in an
earthen crucible. The silica of the crucible is dissolved by the
nitre, the glass thus formed is decomposed by the aluminium,
and the siliceous aluminium thus formed is, as we know, very
oxidizable, and especially in the presence of alkalies. So, the
purification of aluminium by nitre ought to be done in a cast-
iron crucible well oxidized itself by nitre on the inside."
29
45 O ALUMINIUM.
" On mfelting aluminium containing zinc in contact with the
air and at a temperature which will volatilize the zinc, the
largest part of the latter burns and disappears as flaky oxide.
To obtain a complete separation of the two metals it is neces-
sary to heat the alloy to a high temperature in a brasqued cru-
cible. This experiment succeeds very well, but it is here shown
that the aluminium must oxidize slightly on its surface, for
some carbon is reduced by the aluminium from the carbonic
oxide with which the crucible is filled. This carbon thus sep-
arated is quite amorphous.''
Dr. Lisle, of Springfield, O., tested the removal of zinc from
aluminium by distillation and succeeded in obtaining a product
with 98 per cent, of aluminium from which the zinc had been
completely removed. If aluminium containing tin is melted
with lead, the latter sinks with the tin, removing it almost com-
pletely from the aluminium, but the metal remaining retains a
little lead. In an experiment made by the author, aluminium
with 10 per cent, of tin was treated in this way, but the alu-
minium retained nearly 7 per cent, of lead, giving it a blue
color and large crystalline structure. M. Peligot is reported by
Deville to have succeeded in cupelling aluminium with lead,
whereby impure, tough metal became quite malleable. It may
be that the small percentage retained by aluminium when
melted with lead is removed by fusion on a cupel, but I have
been unable to perform any operation with aluminium at all
analogous to the cupellation of silver with lead.
G. Buchner states that commercial aluminium contains con-
siderable quantities of silicon, which by treatment, when melted,
with hydrogen, evolves hydrogen silicide. This does not result
if arsenic is present.
To test this point, I took a sample of aluminium containing 4
per cent, of silicon, and 94 per cent, of aluminium. This was
melted at a low red heat in a sand crucible and hydrogen gas
run in for 12 minutes. On pouring out, the crucible was unat-
tacked, but the metal was identical in color and structure with
that not treated. This was repeated several times, hydrogen
WORKING IN ALUMINIUM. 45 I
gas being passed in as long as 20 minutes with the metal at red
heat, but no apparent change in the purity of the metal re-
sulted.
Similar experiments were made with a current of sulphuretted
hydrogen gas, with a view of removing the iron. No improve-
ment in the looks of the aluminium was apparent. If, however,
air was blown into the melted metal, an improvement was made.
The aluminium was at a bright red heat, and air blown in for 5
minutes, at the end of which time about 5 to 10 per cent, of
dross composed of mixed metal and oxide was formed, and the
remaining metal was whiter, of a finer grain, and evidently much
improved.
Prof. Mallet * made some very accurate estimations of the
atomic weight of aluminium (which he found to be 27.02), and
obtained the chemically pure metal required for his work by
the following process, which is quite applicable when studying
the properties of the pure metal, yet is of course altogether out
of the question as an industrial operation. The purest com-
mercial metal was bought, and on analysis was found to con-
tain—
Aluminium 96.89 per cent.
Iron 1.84 "
Silicon 1.27 "
This was treated with liquid bromine and converted into bro-
mide. This salt was then purified by fractional distillation, the
temperature being very carefully regulated, and the operation
repeated until the product was perfectly colorless, and dissolved
in water without leaving any perceptible impurity. The reduc-
tion was accomplished with difiSculty and much loss by treat-
ing with sodium in a crucible made of a mixture of pure alu-
mina and sodium aluminate. The metal obtained gave on
analysis no weighable quantity of impurities, and the properties
mentioned in Chapters III. and IV. as Mallet's observations are
those quoted from his report on this pure metal.
* Philosophical Magazine, 1880.
45-2 ALUMINIUM.
Professor Le Verrier states * that by a simple fusion of alu-
minium under a layer of an alkaline fluoride the amount of sili-
con is easily diminished. He states that a specimen containing
0.81 per cent, of silicon, contained after one such fusion only
0.57 per cent.
If aluminium is overheated in the crucible, it has a great
tendency to absorb gas (like silver), and gives it out in setting,
producing blow-holes in the castings. It is therefore important
to carefully regulate the temperature of melting. Coehn re-
commends the use of a very small amount of sodium, to take
gas out of the metal, only enough being used to form a thin
film over the melted metal.
Annealing.
By heating to very low redness and cooling quickly, as by
dropping into water, aluminium becomes soft. To get the best
results, the metal should be heated until it just begins to glow
in the dark, or the object is rubbed with a lump of fat, and the
moment that the black trace left by the carbonization of the fat
disappears, the metal is removed from the annealing oven.
Great care is necessary in annealing thin sheets which are being
beaten into leaf, to avoid melting them. Fine wire can be an-
nealed over the chimney of an Argand burner. If it is neces-
sary that the heat must be kept below the point where the
metal would bend and lose its shape, the articles can be heated
in boiling linseed oil and allowed to cool very gradually with
the oil. Very thin sheets or wire can be softened by putting
into boiling water and letting them cool with the water. (See
also pp. 70, 74.)
Hardening.
By hammering, rolling, or drawing, aluminium becomes sen-
sibly harder and stiffer, so that it becomes elastic enough to be
used even for hair-springs for watches. If castings of alumin-
ium are made a little larger than the finished article desired,
♦ Comptes Rendus, July, 1894, p. 13.
WORKING IN ALUMINIUM. 453
and drop-forged cold in dies of the right size, the hardness is
much increased, and it becomes much better able to stand wear
in bearings where great weight does not have to be endured,
e.g., in surveying instruments. Queen &Co., of Philadelphia,
state that they find it best, however, to bush all sockets in alu-
minium castings with brass, when making a bearing or tapping
in a screw.
The most careful tests fail to show the slightest increase in
hardness in metal which has been chilled, as practised with
cast-iron. Surfaces cast in cold, metallic moulds seem as soft
as those cast in sand.
The Eureka Tempered Copper Company of Northeast, Penn-
sylvania, claim that they have hardened aluminium castings in
the same way as they harden copper, but I have seen none
of their work.
Rolling.
Before rolling a bar of aluminium it is well to soften it, and
to taper down a "lead" by hammering. The metal forges well
under the hammer at a low red heat. The metal for rolling had
better be cast into plates in covered iron ingot-moulds, and the
surfaces planed to remove small irregularities. The rolling is
not difficult, except that a large amount of power is required
(about as much for cold aluminium as for hot steel), and as the
metal quickly gets hard it must be annealed often. It is
recommended that the metal be brought warm under the rolls,
and, if possible, elongated lo to 20 per cent, with the first pass,
in order to entirely destroy the crystalline structure of the
metal. The annealing is repeated between each pass until the
sheet is about 3 millimetres thick, after which it can generally
be rolled with fewer annealings, sometimes without any at all.
Rolls warmed to 100-150° C. work better than cold ones. Alu-
minium has been rolled down to the thinness of tissue-paper.
Thin-rolled sheets may be still further extended out by beat-
ing into leaf. The gold-beaters are said to have no special
difficulty in doing this, except that more frequent annealings
454 ALUMINIUM.
are necessary than with gold or silver. M. Degousse was the
first to make this leaf, in 1859; he states that the tempering
must be done by warming only to 100° or 150° C, an actual
glowing heat proving very unsuitable. Aluminium leaf is made
as thin as ordinary gold or silver leaf, and this property would,
therefore, establish aluminium as next to these noble metals in
the order of malleability.
The Mannesmann process of cold rolling is applicable to alu-
minium, by which tubes of all shapes and sizes can be made.
Mr. Elwood Ivins, of Philadelphia, has a special process for
making metallic tubes, which is a sort of rolling process on a
mandril, by which he makes aluminium tubes of any size, shape
or thickness of walls. I have seen a tube made by this process
10 metres long by i millimetre in diameter.
Drawing.
Prof. Thurston places aluminium as sixth in the order of duc-
tility, being preceded by gold, silver, platinum, iron and cop-
per, but it is doublful if it does not rank equally as high as
iron. Deville states that in 1855 M. Vangeois obtained very
fine wire with metal far from being pure. Bell Bros., at New-
castle-on-Tyne, recommended that the metal for drawing be run
into an open mould so as to form a flat bar of about one-half
inch section, the edges of which are beaten very regularly with
a hammer. The diameter should be very gradually reduced at
first, with frequent heating. When the threads are required
very fine the heating becomes a very delicate operation, on ac-
count of the fineness of the threads and the fusibility of the
metal. The gauge should be reduced by the smallest possible
gradations, when wires may be obtained as fine as a hair.
Aluminium tubes are drawn, either round or square, from
sheet which has been soldered together or from cast rings of
the required section ; the first method is said to be preferred.
As the aluminium quickly loses its temper it must be annealed
after each extension.
working in aluminium. 455
Stamping and Spinning.
Aluminium can be spun on the lathe into all sorts of round
and hollow forms ; it may also be pressed or stamped into shape
in the cold ; it is of* advantage in doing this to use a kind of
varnish composed of 4 parts of oil of turpentine and i part of
stearic acid. Soap-water is always to be avoided.
Grinding, Polishing and Burnishing.
When cast carefully it can be filed without fouling the file.
Spun and stamped articles of aluminium can easily be ground
by using olive oil and pumice. A fine steel scratch-brush run
at a high speed will give a good polish to sand castings, and
remove the yellowish streaks that may have been produced by
too hot metal. If sheet metal is thus treated it gives a frosted
appearance, which forms a beautiful finish. Biederman makes
the following remarks on polishing : " The use of the old means
of polishing and burnishing metals, such as soap, wine, vinegar,
linseed-oil, decoction of marshmallow, etc., is not effective with
aluminium, but, on the contrary, is even harmful, because,
using them, the blood stone and the burnishing iron tear the
metal as fine stone does glass. Oil of turpentine has also been
used, but with no good effect. Mourey found, after many at-
tempts, that a mixture of equal weights of olive oil and rum,
which were shaken in a bottle till an emulsified mass resulted,
gave a very brilliant polish. The polishing stone is dipped in
this liquid, and the metal polished like silver, except that one
must not press so hard in shining up. The peculiar black
streaks which form under the polishing stone need cause no
trouble ; they do not injure the polish in the least, and can be
removed from time to time by wiping with a lump of cotton.
The best way to clean a soiled surface and remove grease is to
dip the object in benzine, and dry it in fine sawdust."
Mr. J. Richards found that when buffing in the ordinary way
the dark-colored burnishing powder cut into the metal and
filled its pores with black specks. He found the best means of
456 ALUMINIUM.
burnishing is to use a piece of soft wood soaked in olive oil ;
this closes the grain, and gives a most brilliant finish.
The Pittsburgh Reduction Company polish sheet aluminium
with a sheep-skin, chamois-skin or rag buff, using rouge, the
same as for brass. The particular requisite of a polishing pow-
der for aluminium is that it be very finely ground. This com-
pany sells a polishing powder called "Almeta Polish," which
consists of
Stearic acid i part.
Fuller's earth i "
Rotten stone 6 "
The whole ground very fine and well mixed.
Engraving.
Kerl & Stohman : Aluminium resists the action of the en-
graving tool, which slides upon the surface of the metal as
upon hard glass. But as soon as a varnish of 4 parts of oil of
turpentine and i of stearic acid, or some olive oil mixed with
rum is used, the tool cuts into it as into pure copper.
Cleaning and Pickling: Mat.
Dirt and grease are removed easily by dipping in benzine or
turpentine.
To obtain the beautiful "mat" or frosted efifect, which alu-
minium takes as easily as silver, Deville recommended dipping
for an instant in a very dilute solution of caustic soda, washing
in a large quantity of water, and last dipping in strong nitric
acid. An English writer recommends dipping i^ minutes in
a solution of 3 ounces of caustic potash to a quart of water,
wash thoroughly, and then dip in a mixture of 3 measures
strong nitric acid to 2 measures sulphuric acid. By the above
treatments, any elements which might contaminate the alumin-
ium, except a very large proportion of silicon, are dissolved
from the surface. If, as Mourey recommends, some hydroflu-
oric acid is added to the nitric, the silicon is more actively
attacked.
working in aluminium. 45 7
Welding.
Aluminium cannot be welded except by the electrical pro-
cess, and then only with difficulty. The high electric conduc-
tivity, the high specific heat and latent heat of fusion, and par-
ticularly the mushy state into which the metal passes some
considerable time before its real melting point, make the oper-
ation hard to perform satisfactorily. In the early days of elec-
tric welding it could not be done at all, but the Thomson Elec-
tric Welding Company state that they have constructed a
special machine for this kind of material, and can now make
the welds rapidly and satisfactorily.
Soldering Aluminium.
A satisfactory solder for use on any metal should fill the fol-
lowing requirements :*
1. It should fuse readily.
2. It must alloy easily with the metal; in common parlance,
it must bite.
3. It must be tough.
4. It must not disintegrate.
5. It should be of the same color as the metal.
6. It should not discolor with age.
7. It should not be too expensive.
Aluminium is a difficult metal to solder properly for three
particular reasons :
I. It is difficult to expose a bare surface of aluminium to the ^
action of the solder. Grease and dirt can be easily enough
removed, but there is always present a thin, continuous coating
of alumina which effectually prevents the solder from getting
to the metal beneath. It might be thought that a thorough
sand-papering or fiHng of the surfaces immediately before sol-
dering would overcome this, but we find it of absolutely no
use ; the reason is that the thin, invisible skin of alumina forms
* For a more extended essay on the properties of a good solder, see a paper by the
writer in the "Aluminium World," New York, October, 1894.
458 ALUMINIUM.
instantly, as quickly as the metal is laid bare. The ordinary
fluxes used in soldering have no effect at all on this coating.
To overcome this difficulty, it is necessary either to use some
particular flux which can remove this oxide and preserve the
surface clean until the solder can take hold, or else to incor-
porate into the composition of the solder some ingredient
which can do the same thing. The latter device has been the
most successful, as theoretically it should be ; for if the solder
as it were carries its own flux, the action of the flux and the
taking hold of the solder must be simultaneous, and therefore
most effective.
2. Aluminium has a high conductivity for heat. This inter-
feres greatly with the attempt to produce a local temperature
at the joint high enough for the solder to alloy ; which causes
the solder to chill quickly in the joint, particularly when work-
ing on bulky articles. The only way to overcome this diffi-
culty is to use very hot soldering-bolts and to work slowly, so
as to get the metal at the joints hot.
3. Aluminium is highly electro-negative. This property
causes the first difficulty, the instantaneous formation of a thin
skin of oxide, but it also operates in another way after the joint
is made. It causes galvanic action to arise at the joint between
the aluminium and the solder, and causes the joint to weaken
rapidly. To render this action as small as possible, the solder
should be made as far as practicable of metals near to alu-
minium in the galvanic series, such particularly as zinc.
With the preceding introduction to the subject, we will con-
sider the various solders which have been proposed and used,
giving first Deville's views on the question, for even at the time
of writing his book (1859), the difficulty of soldering alumin-
ium properly was regarded as one of the greatest obstacles to
its industrial employment.
Deville : " Aluminium may be soldered, but in a very im-
perfect manner, either by means of zinc, or cadmium, or alloys
of aluminium with these metals. But a very peculiar difficulty
arises here — we know no flux to clean the aluminium which
WORKING IN ALUMINIUM. 459
does not attack the solder, or which, protecting the solder,
does not attack the aluminium. There is also an obstacle in
the particular resistance of aluminium to being wetted by the
more fusible metals, and on this account the solder does not
run between and attach itself to the surfaces to be united. M.
Christofle and M. Charriere made, in 1855, during the Exposi-
tion, solderings with zinc or tin. But this is a weak solder and
does not make a firm seam. MM. Tissier, after some experi-
ments made in my laboratory, proposed alloys of aluminium
and zinc, which did not succeed any better. However, M.
Denis, of Nancy, has remarked that whenever the aluminium
and the solder melted on its surface are touched by a piece of
zinc, the adhesion becomes manifest very rapidly, as if a partic-
ular electrical state was determined at the moment of contact.
But even this produces only weak solderings, insufficient in
most cases."
" A long time ago, M. Hulot proposed to avoid the difficulty
by previously covering the piece with copper, then soldering
the copper surfaces. To efifect this, plunge the article, or at
least the part to be soldered, into a bath of acid sulphate of
copper. Put the positive pole of a battery in communication
with the bath, and with the negative pole touch the places to
be covered, and the copper is deposited very regularly. M.
Mourey has succeeded in soldering aluminium by processes yet
unknown to me ; samples which I have seen looked excellent.
I hope, then, that this problem has found, thanks to his ingenu-
ity, a solution ; a very important step in enlarging the employ-
ment of aluminium."
Mourey's first practicable solders for aluminium were of zinc
and aluminium, and of two kinds — hard and soft. He used a
soft solder to first unite the pieces, and afterwards finished the
soldering with a less fusible one. These solders contained —
I. II.
Aluminium 20 15
Zinc 80 85
The alloys with the larger proportion of zinc are the easiest
III.
IV.
V.
12
8
6
88
92
94
46o ALUMINIUM.
melting or softest ones, one such as IV. being used for ordin-
ary work, while II. was used for brazing. These solders have
the disadvantage that on melting they oxidize very easily, and
in consequence of the film of oxide thus formed the work is so
much more difficult. This difficulty can be overcome by dip-
ping the small grains of solder in copaiva balsam and turpen-
tine, which keep out the air, and act as reducing agents during
the operation. The new solders subsequently used were sim-
pler in application, for the work was finished with one solder
and the moistening with balsam was rendered unnecessary.
Mourey improved upon the zinc-aluminium solders by add-
ing copper, using five different alloys of these three metals ac-
cording to the objects to be soldered. They contained —
I. II. III. IV. v.
Aluminium 12 9 7 6 4
Copper 8 6 5 4 2
Zinc 80 85 88 90 94
The following directions are given for preparing these alloys:*
" To make the solder, first put the copper in the crucible.
When -it is melted, then add the aluminium in three or four
portions, thereby somewhat cooling the melted mass. When
both metals are melted, the mass is stirred with a small iron
rod, and then the required quantity of zinc added, free from
iron, and as clean as possible. It melts very rapidly. The
alloy is then stirred briskly with an iron rod for a time, some
fat or benzine being meanwhile put in the crucible to prevent
contact of the metal with air and oxidation of the zinc. Finally
the whole is poured out into an ingot mould previously rubbed
with benzine. After the addition of zinc, the operation must
be finished very rapidly, because the latter will volatilize and
burn out. As soon as the zinc is melted the crucible is taken
out of the fire. Only zinc free from iron can be used, since
even an apparently insignificant amount of this impurity injures
the qualities of the solders very materially in regard to dura-
bility and fusibility.
* Das LSthen, by Edmund Schlosser, \ ienna, 1880, p. loi.
WORKING IN ALUMINIUM. 46 1
" The separate pieces of metal to be soldered together are
first well cleaned, then made somewhat rough with a file at the
place of juncture, and the appropriate solder put on it in pieces
about the size of millet grains. The objects are laid on some
hot charcoal, and the melting of the solder effected by a blast
lamp or a Rochemont turpentine-oil lamp. During the melt-
ing of the solder, it is rubbed with a little soldering iron of
pure aluminium. The soldering iron of pure aluminium is
essentially a necessity for the success of the operation, since an
iron of any other metal will alloy with the metals composing
the solder, while the melted solder does not stick to the iron
made of aluminium.
" For quite small objects, as for jewelry, solder I. is used ; for
larger objects and ordinary work IV. is more suitable, and is the
solder most used. These alloys work so perfectly that plates
soldered together never break at the joint when bent back and
forth, but always give way in other places ; which is a result
not always possible in the best soldering of plates of silver."
Bell Bros, used the above solders in their works at Newcastle,
and in a description of the soldering operation state the follow-
ing facts in addition to those already given :* " In the operation
of soldering, small tools of aluminium are used, which facilitate
at the same time the fusion of the solder and its adhesion to
the previously prepared surfaces. Tools of copper or brass
must be strictly avoided, as they would form colored alloys
with the aluminium and the solder. The use of the little tools
of aluminium is an art which the workman must acquire by
practice. At the moment of fusion the work needs the appH-
cation of friction, as the solder suddenly melts very completely.
In soldering it is well to have both hands free, and to use only
the foot for the blowing apparatus."
We also find the following alloys credited to Mourey as used
by him for soldering aluminium, probably with the blow-pipe :t
* Chemical News, iv., 81.
t Dingier, 166, 205.
462 ALUMINIUM.
Aluminium 30 20
Copper 20 15
Zinc 50 65
While it is true that Mourey received from the Societe
d'Encouragement a prize for the solders he had found, and
while they were the best then in use, yet every one knows that
they were not satisfactory. Their melting points were too high,
and it required great skill to make neat joints. Even as late as
1890 we find a writer saying, " The want of a suitable solder for
aluminium has greatly retarded its use in the arts," although
many attempts had meanwhile been made to provide solders
superior to Mourey's.
Col. Wm. Frishmuth * recommends a solder containing: —
Aluminium 20
Copper 10
Zinc 30
Tin 60
Silver 10
Later, Col. Frishmuth f states that the solder just given is
used for fine ornamental work, while for lower-grade work he
uses the following : —
Tin
Bismuth .
I.
II.
III.
95
97
98-99
S
3
' 2-1
He recommends for a flux, in all cases, either paraffin, stearin,
vaselin, copaiva balsam, or benzine. In the solder for fine
work, if aluminium is used in larger quantity than recom-
mended, the solder becomes brittle.
Schlosser % recommends two solders containing aluminium as
especially suitable for soldering dental work, on accbunt of
their resistance to chemical action. Copper cannot be allowed
in alloys intended for this use, or only in very insignificant
* Techniker, vi. 249.
t Wagner's Jahresb., 1884.
X Das Lothen, p. 103.
WORKING IN ALUMINIUM. 463
quantity, since it is so easily attacked by acid food, etc. Since
these two alloys can probably be used also for aluminium dental
work, we subjoin their composition —
Platinum-aluminium solder. Gold-aluminium solder.
Gold 30 Gold.' 50
Platinum I Silver 10
Silver 20 Copper 10
Aluminium 100 Aluminium 20
M. Bourbouze states that the difficulties met with in solder-
ing aluminium are satisfactorily overcome by the following
process : —
*"The parts to be united are subjected to the ordinary op-
eration of tinning, except that in place of pure tin an alloy of
tin and zinc, or, better, of tin, bismuth and aluminium is used.
However, preference is given to an alloy of tin and aluminium,
mixed in different proportions to suit the work put on the joint.
For those which are to be subsequently worked, an alloy of 45
parts tin and 10 parts aluminium should be used. This solder
is malleable enough to resist hammering, drawing, or turning.
Pieces not to be worked after soldering may, whatever the
metal to be united to the aluminium, be solidly soldered with a
tin solder containing less aluminium. Neither of these solders
requires any preparation of the pieces, and the last one may
be applied with a common soldering-iron. To unite other
metals to aluminium it is best to coat the part with pure tin,
the aluminium is coated with one of the above alloys, the joint
closed and finished by heating in the usual manner."
O. M. Thowless has patented the following solder for alu-
minium, and method of applying it:t The alloy is com-
posed of —
Tin 55 parts.
Zinc 23 "
Silver 5 "
Aluminium., 2 "
* Comptes Rendus, 98, 1490.
t English Patent, 10,237, ^""S- '9> '885.
464 ALUMINIUM.
The silver and aluminium are first melted together, the tin
added, and lastly the zinc. The metallic surfaces to be united
are immersed in dilute caustic alkali or a cyanide solution,
washed and dried. They are then heated over a spirit lamp,
coated with the solder and clamped together, small pieces of
the alloy being placed around the joints. The whole is then
heated to the melting point of the solder, and any excess of it
removed. No flux is used.
J. S. Sellon patents the following method:* The aluminium
surfaces are cleaned by scraping and covered with a layer of
paraffin wax as a flux. They are then coated by fusion with a
layer of an alloy of zinc, tin and lead, preferably in the propor-
tions—
Zinc 5
Tin 2
Lead :
The metallic surfaces thus prepared are soldered together in
the usual way with any good solder.
C. Sauer, of Berlin, patents the following :f An alloy is
made of
Aluminium 9 parts.
Silver i, 2, 3 or 4 "
Copper 2, 3, 4 or 5 "
He also claims the above alloy, to which is added i or 2 parts
of zinc, cadmium or bismuth, or even of a fusible metal such as
Wood's alloy. A small proportion of gold may be added. In
making, the copper and silver are first melted, molten alumin-
ium, added and the solid zinc last dropped in. In using, the
alloy is broken small, spread between the surface to be sold-
ered, previously heated, and the joint then made with a solder-
ering-iron. No flux is required.
J. Novell states that the following alloys can be used on alu-
minium, aluminium bronze or for any other metals:
* English Patent, 11,499, Sept. 26, 1885.
t English Patent, 8,551, May 5, 1892.
I Comptes Rendus, 116, 256.
WORKING IN ALUMINIUM. 465
Melting point.
No. I. Pure Tin 235° C.
2. Tin 1000, Lead 50 280-300°
3. Tin 1000, Zinc 50 280-330°
4. Tin 1000, Copper 10 to 15 350-450°
5. Tin looo, Nickel 10 to 15 ~. 350-450°
6. Tin 900, Copper 100, Bismuth 2 to 3 350-450°
Nos. I, 2, and 3 are for pure aluminium, having a white
color ; Nos. 4 and 5 are harder and stronger, but are light-yel-
low; No. 6 is yellow, and best adapted for soldering aluminium
bronze.
By reference to Deville's statement, (p. 459), it will be seen
that aluminium was soldered with tin in 1855, but the joints
were found too weak ; and it has been the writer's experience
that such joints quickly disintegrate and fall apart.
Mr. C. H. Land, of Detroit, Mich., states, however, that
joints of pure tin can be made strong and permanent by oper-
ating in the following manner : * The pieces of aluminium to be ■
soldered are immersed in molten tin, and while submerged, the
parts to be soldered rubbed briskly with a brush having steel
bristles. This removes the skin of oxide and permits the tin
to unite firmly with the aluminium. Edges thus treated can be
sweated together or soldered together with ordinary solder.
Aluminium can thus be soldered also to copper, brass, galvan-
ized-iron or cast-iron. It is stated by Mr. Laird that joints
made four years ago are still strong, and show no signs of
coming apart. Since the writer's experience with pure tin used
in the ordinary way is just the reverse of this, it may be that
the wetting of the edges by rubbing in the molten tin is of
great benefit in producing a permanent joint. Exactly the
same method of procedure was patented in England by L.
Oliven, more than two years later, f
The Aluminium Company at Neuhausen, Switzerland, put
on the market in 1890 specially-prepared sheet aluminium,
*U. S. Patent, 440,952, Nov. 18, 1890.
t English Patent, 23,477, Dec. 20, 1892.
30
466 ALUMINIUM.
which was easier to solder .than ordinary aluminium. The
special preparation was not divulged, but I have heard that
aluminium containing I or 2 per cent, of zinc solders more
easily than the pure metal. The edges to be joined were not
scraped, but a flux of resin, tallow and zinc chloride was to be
used. The same firm also recommended depositing a thin film
of copper on the edges to be joined, and then soldering on
the copper. The trouble with this device is that the copper
is apt to shell off by the sudden heating. The same firm also
subsequently recommended the use of cadmium chloride as
a flux, when doing blow-pipe work, but this salt quickly
absorbs moisture from the air and becomes worthless for the
purpose.
Otto Nicolai, of Wiesbaden, and Carn Langenbach, have
patented * the use of the chloride, sub-chloride, bromide or
iodide of silver as a flux. Their action would be, of course, to
deposit metallic silver on the aluminium. The salt is strewn
as powder along the joint, and the soldering done with any
good solder. The use of silver chloride in this way was
patented in the United States previous to the above, date. The
flux is certainly of advantage to use, but is too expensive for
ordinary work.
Wegner and Guhrsf recommend using as a flux a mixture
of 80 parts stearic acid, 10 parts zinc chloride, and 10 parts
stannous chloride, SnCl^. They claim excellent results wiien
this is used with a solder of 80 parts tin to 20 zinc.
E. Werner, of Hamburg, | proposes to use as a flux when
soldering aluminium the cyanide of the metal used as solder,
e. g., cyanide of tin. The solder and flux are strewn along the
joint and melted with the blow- pipe.
B. I. Roman § patents a solder composed of zinc 50 parts,
* English Patent, 16,292, Sept. 12, 1892.
t English Patent, 512, Jan. 10, 1893.
X German Patent, 75,659.
§ English Patent, Sept. 19, 1893, No 17,623.
WORKING IN ALUMINIUM. 467
tin 34, aluminium 9, nickel 5, silver 2. No flux is used with
it, and an aluminium bolt is recommended.
The Alsite Aluminium Solder, made in New York, was ex-
tensively advertised during 1893 and 1894, and at a demonstra-
tion before the Franklin Institute, Philadelphia, the inventor did
some very neat and solid work with it, using the blow-pipe.
The melting point, however, was high, and considerable skill
was required to use it. The composition was not divulged.
After the lapse of a year, however, the work done has tumbled
apart by the disintegration of the solder, and even the bar of
solder itself has become black and so brittle that it will not
support its own weight.
The writer's father, Mr. Joseph Richards, of the Delaware
Metal Refinery, Philadelphia, one of the most extensive makers
of lead-tin solder in the United States, has experimented a great
deal with aluminium solder, and finally concluded that a small
amount of phosphorus was a great improvement to any other
solder hitherto used. The composition has been patented in
the United States and England * and describes as preferable a
solder composed of —
Tin 32 parts = 78.34 per cent, tin
Zinc 8 parts = 19.04 " zinc.
Aluminium i part = 2.38 " aluminium.
Phosphor tin I part = 0.24 " phosphorus.
On re-melting some of this solder, a liquation was noticed,
and it was inferred that the more fusible part was probably a
better alloy for soldering, being less likely itself to liquate. It
was therefore analyzed, and found to contain 71.65 per cent, of
tin, corresponding closely to the formula Sn^Zns, which would
call for 70.7 per cent. The solder as now made contains i
part aluminium, i part phosphor tin, 1 1 parts zinc and 29 parts
tin, giving it 71.2 per cent, of tin.
As regards the use of this solder, it may be said that it fills
most of the conditions of a satisfactory solder. It fuses easily,
» United States Patent, 478,238, July 5, 1892; English Patent, 20,208, of 1892.
468 ALUMINIUM.
at a heat attainable witji a copper or nickel bolt ; it has a won-
derful ability to take hold on the metal, for I have heated a
piece of sheet aluminium and then firmly traced my name on
it with a stick of solder used as a pencil ; it is so tough that if
a joint is well made the metal will break before the solder ; it
does not disintegrate, for joints made three years ago are still
firm ; it is very nearly the color of aluminium, but darkens
slightly on standing some time ; when the article is in constant
wear, however, the solder retains its bright color, or when dis-
colored it becomes bright again by polishing ; the solder is not
expensive. Joints may be made with the bolt, the blow-pipe,
or by sweating together. The edges to be joined are filed or
scraped clean immediately before soldering, then, if the piece
will allow, heated to a temperature at which the solder melts and
the edges are tinned by rubbing with a stick of solder. If the
whole piece cannot be heated, the edges can be tinned by heat-
ing with a tinned bolt, and rubbing in the melted solder briskly.
Any surplus solder is removed from the edges by a small
scraper, while still hot. The prepared edges are then soldered
together in any way desired. For a lap-joint, the edges are
over-lapped, the soldering bolt passed along, and a little extra
solder melted in the joint. For a joint at an angle, it is neces-
sary that the bolt be shaped to fit, as the solder must be rub-
bed in well at the edges. No flux of any kind is to be used
either on the bolt or the joint. In making a lock-seam, the
edges of the aluminium should be coated with the solder as
above described before being turned over, else the solder can-
not soak into the joint. Common sheet-tin does not need such
preparation, because the whole sheet is already tinned to start
with. In brief, to put it in a way which any tinsmith can un-
derstand, aluminium is similar to copper and black-iron, not
like tinned iron, and the edges to be joined must be prepared
for soldering. The solder answers equally well for uniting alu-
minium to copper, brass, German-silver, steel or cast-iron,
which work has been repeatedly performed, and found to make
a permanently good joint.
WORKING IN ALUMINIUM. 469
This solder is sold in Great Britain by Mr. Archibald Briggs,
of Dundee, Scotland, and on the Continent by the Aluminium
Industrie Actien-Gesellschaft at Neuhausen, Switzerland. Dr.
Kiliani, director of the latter's works, pronounced it the only
satisfactory solder for use with the bolt. It is the only solder
used by the large makers of aluminium goods, and its use is
increasing rapidly with the growth of the aluminium industry.
Coating Metals with Aluminium.
Many attempts have been made to give baser metals a thin
coating of aluminium and thus impart to them superficially the
resisting properties of that metal. We may distinguish broadly
two different methods of procedure used to accomplish this —
the chemical (and electric) and the mechanical. Aluminium
is not thrown down in a metallic state from its solutions by any
other metal, and therefore it cannot be obtained as a plating
by dipping the article in any solution of its salts. It can, how-
ever, be deposited electrically from aqueous solutions, using
soluble aluminium anodes, as has been already described in
Chapter XI.
Aluminium can also be deposited electrolytically in the solid
state from a fused bath of its chlorides, etc., but, although
Deville says that this principle can be utilized for coating other
metals with aluminium, yet the metal is never deposited in a
dense, compact film, but more or less as a powder mixed with
carbon and other impurities, and satisfactory results cannot be
obtained. The mechanical methods alluded to are conducted
in two ways, either by uniting thin sheets of aluminium to the
surface of another metal (veneering), or by using aluminium
powder and burning in (aluminizing).
Of the practice of veneering with aluminium, Deville says in
1859: "M. Sevrard succeeded in 1854 in plating aluminium
on copper and brass with considerable perfection. The two
metallic surfaces being prepared in the ordinary manner and
well scoured with sand, they are placed one on the other and
held tightly between two iron plates. The packet is then
470 ALUMINIUM.
heated to dark redness, at which temperature it is strongly
compressed. The veneer becomes very firmly attached, and
sheets of it may be beaten out. I have a specimen of such
work perfectly preserved. The delicate point of the operation
is to heat the packet just to that point that the adherence may
be produced without fusing the aluminium, for when it is not
heated quite near to this^fusing point the adherence is incom-
plete. Experiments of this kind with copper and aluminium
foil did not succeed, for as soon as any adherence manifested
itself the two metals combined and the foil disappeared into
the copper. In an operation made at too low a temperature,
the two metals, as they do not behave similarly on rolling, be-
come detached after a few passes through the rolls. Since
then, the experiments in veneering aluminium on copper, with
or without the intervention of silver, have succeeded very
well." Deville stated later, in 1862, that Chatel had brought
this art to perfection, the veneered plates being used largely
for reflectors, etc., in place of silver-plated material.
Dr. Clemens Winckler * gives his experience in this line as
follows: "The coating of other metals with aluminium by the
so-called plating method is, according to my own experience,
possible to a certain degree, but the product is entirely useless,
every plating requiring an incipient fusing of both metals and
their final intimate union by rolling. The ductility of alumin-
ium is, however, greatly injured by even a slight admixture
with other metals ; iron makes it brittle, and copper, in small
per cent., makes it fragile as glass ( ?). If now it were possible
in any way to fuse a coating of aluminium upon another metal,
there would be formed an intermediate alloy between the two
metals from which all ductility would be gone and which would
crumble to powder under the pressure of the rolls, thus separat-
ing the aluminium surface from the metal beneath. But even
if it were possible in this way to coat a metal with a thin plate,
it is still doubtful if anything would be attained thereby. For,
* Industrie Blatter, 1873.
WORKING IN ALUMINIUM. 4/1
while compact aluminium resists oxidizing and sulphurizing
agencies, the divided metal does not. In powder or leaves
aluminium is readily oxidized, as is shown by its amalgam
becoming heated in the air and quickly forming alumina. In
the form of a coating upon other metals it must necessarily be
in a somewhat finely divided state, and hence would probably
lose its durability."
Dr. G. Gehring* has patented a method of aluminizing by
which difficultly-fusible metals, stone-ware or the like, can be
coated with aluminium. A mixture is made of a fatty acid
(sebacic) and acetic acid with clay, etherized oil and alumin-
ium (or aluminium bronze) in powder. This is spread evenly
on the metal or object to be treated and then heated with a
Bunsen burner using blast or in a muffle. The coating pro-
duced is silver white, does not oxidize under ordinary condi-
tions, stands heating in an ordinary fire, and can be highly pol-
ished. It is stated! that this process is now largely made use
of in Germany.
Somewhat analogous results are obtained by Brin Bros, (p.
417) without the use of metallic aluminium (similar to those
claimed also by Baldwin, p. 426), but while in Dr. Gehring's
process the coating would be formed on any surface, in these
other processes the presence of the metallic base is necessary,
and an alloy with a few per cent, of aluminium is formed on the
surface of the object and penetrates a little way into its interior.
Such a coating, then, is simply a transformation of the outer
layer of metal into an alloy with a small quantity of alumin-
ium, and could possess very few of the qualities of aluminium,
but might possess, as an alloy, qualities superior to those of
the original metal.
H. C. Broadwell, oi Philadelphia, claims that sheet-iron can
be coated with aluminium by first cleaning the iron carefully,
then immersing it in a bath of molten aluminium, and while im-
mersed rubbing its surface vigorously with a steel brush. If a
♦German Patent, 29,891 (1885).
t Engineering and Mining Journal, Feb. 13, 1886.
472 ALUMINIUM.
temperature over a red-heat is used, the iron will probably be
attacked, because this happens when melting aluminium in an
iron crucible (p. 444). I cannot learn, however, that the pro-
cess has been applied on a commercial scale. If such a pro-
cess could be made practicable, we should have in the alu-
minium-coated plates a rustless substitute for tinned sheet-iron,
the only drawback to which would be that it is not so easily
soldered as sheet-tin.
Plating on Aluminium.
Deville says: "The gilding and silvering of aluminium by
electricity is very difficult to do satisfactorily and obtain the
desirable solidity. M. Paul Morin and I have often tried it by
using a bath of acid sulphide of gold or of nitrate of silver
with an excess of sulphurous acid. Our success has only been
partial. However, M. Mourey, who has already rendered great
services in galvano-plasty, gilds and silvers the aluminium of
commerce with a surprising perfection, considering the little
time he has had to study the question. I also know that Mr.
Christofle has gilded it, but I am entirely ignorant of the
methods employed by these gentlemen.* The coppering of
aluminium by the battery is easily effected by M. Hulot by
using an acid bath of sulphate of copper."
Tissier Bros, state that aluminium can be gilded without using
a battery by preparing a solution as follows : " Eight grammes
of gold are dissolved in aqua regia, the solution diluted with
water and left to digest twenty-four hours with an excess of
lime. The precipitate, with the lime, is well washed, and then
treated with a solution of twenty grammes of hyposulphite of
soda. The liquid resulting serves for the gilding of aluminium
without the aid of heat or electricity, the metal being simply
immersed in it after being previously well cleaned by the suc-
cessive use of caustic potash, nitric acid, and pure water."
* M. Mourey has since stated that his means are galvanic, and that be has no
trouble in depositing silver and gold in six different colors — shining, matt, or dull —
but does not describe his methods.
WORKING IN ALUMINIUM. 473
Aluminium can be veneered with other metals in a manner
strictly analogous to the reverse process described by Deville.
For example, Morin describes the veneering with silver as fol-
lows : " Sheet silver is laid on the clean aluminium surface, a
steel plate placed over the silver, and the whole bound into a
packet with fine copper wire. Two large cast-iron blocks are
heated to a dark red heat, the packet placed between them and
a pressure of i ton to the square centimetre (lo tons per
square inch) applied gradually and sustained for 15 minutes.
When removed from the hydraulic press they can be rolled like
silvered copper when brought to the proper heat. The plating
with gold succeeds best if a thin leaf of silver is slipped be-
tween the two sheets of metal, the operation proceeding then
exactly as above. Platinum may be plated on aluminium just
as easily as silver."
The firm of J. and A. Erbsloh, of Barmen-Wupperfield, Ger-
many, put on the market copper-sheet on which aluminium has
been rolled, but they keep their mode of procedure secret.
They also roll together gold and silver with aluminium.
Wegner and Guhrs, of Berlin, plate aluminium electrolyti-
cally with gold, silver, nickel, copper, bronze or brass. Their
process has been very successful in practice, depositing directly
on the aluminium. The baths recommended are solutions con-
taining potassium cyanide, and require less than the ordinary
power for precipitation. The same investigators have discov-
ered processes for coloring aluminium black, brown, or almost
any other shade, the colors being permanent.
Neeson, a German chemist, recommends first dipping the
aluminium in alkali till bubbles of gas appear, then into a solu-
tion of corrosive sublimate, then again into the caustic, and
finally into a salt of the desired metal, which is then deposited
on the aluminium as an adherent film.
Uses of Aluminium.
Deville wrote in 1862: "Aluminium is the intermediate
metal between the noble and the base metals." This was true
474 ALUMINIUM.
then of its price as well as of its properties ; it does not with-
stand chemical agents in general as strongly as the noble
metals, but it withstands air, water, sulphuric acid, nitric acid
and sulphuretted hydrogen — which is not the case with iron,
copper, or even silver. We have then a semi-noble metal ; but
while silver, gold and platinum have extremely small prospect
of becoming noticeably cheaper, yet the time is probably not
far distant when we shall have our semi-noble metal at the price
of the base ones. This affords the immense future for alumin-
ium. Whatever its price, it can only replace gold or platinum
because of its lightness ; it already replaces silver especially be-
cause of its resistance to sulphur, as well as for its lightness,
besides being cheaper ; it can only replace the common metals,
at its present price, for uses where its lightness is an extraordi-
nary advantage. But when its price is down to that of these
baser metals, it will begin to replace them by virtue of its other
superior qualities, chemical and physical ; aside from its light-
ness it will win a large field simply in comparison with them on
its merits as a metal. Thus, there are wide applications now
almost unthought of, because the high price has been a blank
wall to stop its use ; but as it cheapens more and more, we hear
every day of new uses brought to light. Thus its sphere will
widen until, since its ores are as cheap as those of iron, it will
approximate in utility to that universal metal. At the time of
this writing, (1895) there are only four metals which are cheaper
bulk for bulk than aluminium ; viz. : iron, zinc, lead and copper ;
and the amount of aluminium produced yearly is increasing
much more rapidly than any of these. Aluminium has there-
fore already won its place among the common metals of every-
day life. It will, of course, be many years before it outstrips
any of these, but I believe the ultimate goal of aluminium in-
dustry will be reached only when it stands next in importance
and value of annual production to iron. From this time forth,
every year will see substantial advance towards this goal, and
the next century may see this end attained.
Chronologically, the first article made of aluminium was a
WORKING IN ALUMINIUM. 475
baby-rattle intended for the infant Prince Imperial of France,
in 1856. For this purpose it no doubt answered excellently,
from its brightness, lightness, ring and cleanliness, but only a
prince could afford to possess one in those days. In the next
few years it was used for all sorts of articles of ornament and
luxury. It was found well-suited for fine jewelry by reason of
its adaptability to being cast and carved, the beautiful reflec-
tions from a chased surface, its color, matching well with gold,
and the absence of odor. But it did not keep its polish so well
as gold, and perhaps more to the point, it did not stay in fash-
ion long; so that the rage for aluminium jewelry subsided al-
most as fast as it had arisen, and it is only quite lately that it is
being used again in this way to any extent. Then the French,
with their ability for producing artistic furniture, used it for in-
laid work on carved mouldings, cabinets, table tops, etc., 'but
this application never exceeded a limited extent.
It is said that the Emperor's interest in aluminium, in 1854,
was aroused partly by the idea that if it could be had cheaply
it would wonderfully lighten the weight of military equipments,
such as spurs, buttons, sword-handles, sabre-sheaths, helmets,
and the imperial eagles. A helmet was made for the Empe-
ror's cousin, the King of Denmark, which when gilded, orna-
mented, and fitted up complete, weighed only one and one-fifth
pounds. The weight of the imperial eagles was lessened from
eight pounds to nearly three pounds, it being remarked that
" since they were gilded, only the bearer perceived the differ-
ence." When Garopon, in Paris, was furnished with very fine
wire by Vaugeois, he was immediately successful in working it
into embroidery, lace and passementerie. This use of alumin-
ium has also a military bearing, since aluminium wire can be
used instead of silver in embroidering banners, and especially
in working figures and epaulets on soldiers' uniforms.
Military uses. — Within the last five years, several govern-
ments have taken up the questfon of aluminium for military
uses. The Germans have taken the initiative. They appointed
a commission to test its suitability for canteens, cooking uten-
476 ALUMINIUM.
sils, pontoons, and, in fact, almost every other metallic part of
a soldier's equipment. As a result of this inquiry the German
army is being permanently equipped with aluminium cooking
utensils, canteens and pontoons. Every ounce of weight thus
saved means as many more cartridges carried per man. In the
Russian army, ammunition wagons with aluminium frames are
being tried. The United States have not officially adopted any
aluminium articles in their military service, but Lieut. Brown
has been making many of the service articles in aluminium and
sending them to headquarters at Washington. It is to be
hoped that his efforts will be successful, and that our country
will not be behind Europe in increasing in every way the com-
fort and efficiency of the military.
Naval use. — Within a very short time it has become possible
to build aluminium vessels. Escher, Wyss & Co., of Zurich,
were the first in this line, building a naphtha launch entirely of
aluminium, even to its smoke-stack and rigging. Several others
have been built by the same firm ; also, a sailing yacht and a
flat-bottomed boat for inland navigation in Africa. The naph-
tha yacht " Mignon" built by them is 43 feet long, 6 feet beam,
draft 2 feet 2 inches. The keel, stern and stern posts are of
forged aluminium with a section of 7 in. by i in. The frames
are angles of i inch wide by i inch deep, one-sixteenth inch
thick. The shell is three thirty-seconds of an inch thick. The
whole is held together by aluminium rivets. The rigging is
of aluminium wire, not painted. All the machinery is of alu-
minium, including the propeller, except the cranks and shaft-
ing. The engine is 6 horse-power, and on the trial trip the
boat attained a speed of eight miles an hour. A writer in
Dingler's Polytechnic Journal compares 3 yachts of 10 tons
displacement, made respectively of wood, steel and aluminium.
He finds that the light frame of the latter permits heavier bal-
last, thus lowering the centre of gravity, and increasing the
stability. In reckoning the cost, the value of the worn-out hull
was not considered, and aluminium was taken at its price in
1892, which is 50 per cent, above its present price.
WORKING IN ALUMINIUM. 477
Wood. Steel. Aluminium.
Relative cost 1.0 i.o 1.8
Centre of gravity below water 0.43 m. 0.47 m. 0.65 metre.
Relative sail area i.oo 1.06 1.35
Relative speeds i.oo 1.03 1.16
The calculation with regard to the stability, as shown by the
lowering of the centre of gravity, will hold for any type of
vessel.
The Vendenesse, a sea-yacht constructed at Saint-Denis,
France, in 1892, built for Count Chabonne, is of 12 tons dis-
placement, contains a little over one ton of aluminium, a sav-
ing in weight over steel or wood of two tons. A prolonged
stay in the harbor at Havre has proven that the sea water has
practically no effect on the hull, and with 1 1 tons of lead in
the keel there was no straining or weakening in a heavy sea.
Immediately thereafter the French Minister of the Marine de-
cided to have an aluminium torpedo boat constructed, to be
carried by the warship La Foudre. This was built by Yarrow
& Co., and had its trial trip in September, 1894. The vessel is
60 feet long, 9 feet three inches in depth. The aluminium was
strengthened by being alloyed with 6 per cent, of copper, which
increased its tensile strength to 35,000 pounds per square inch.
All frames were made 25 per cent, larger than if they were
steel, and therefore weighed exactly one-half as much. The
weight of the hull alone was reduced from 4 tons to 2 tons.
The extra cost of the material, compared with steel, was $5000,
for the whole boat, in return for which there was a saving of 2
tons in dead weight and an increase of 3.5 knots in speed over
vessels of the same class and dimensions made of steel. The
maximum speed attained was 22.2 knots, and the average 20.5
knots. The total weight with steam up and coal in the bunkers
is 10 tons, the horse-power of the engines 300.
While this torpedo boat is the largest vessel so far constructed
in aluminium, yet we may expect in the near future to hear of
still larger ones, particularly pleasure steam-yachts, being con-
-structed of it. At the same time we must not omit to mention
478 ALUMINIUM.
the aluminium boats constructed by Rossiter & Co., of Balti-
more, for the explorer Wellman, and which did such good ser-
vice in the battle with ice and frost that he ha^ nothing but
praise for them ; nor the aluminium rowing-shells built by
Galanaugh, of Philadelphia, in one of which the local champions
lowered their course record 8 seconds the first time they rowed
in it. Hunting boats and small row-boats are being made at
present in considerable numbers.
The yacht "Defender," which defended the American Cup
against the English yacht Valkyrie III, in 1895, has its hull of
aluminium-bronze plates to the water hne, and aluminium plates
alloyed with 3 per cent, of nickel above the water line. The
upper frames and deck beams are also of the nickel alloy. The
aluminium work is very properly protected by painting. This
is undoubtedly the staunchest and fastest racing yacht ever
built.
Vehicles. — For apparatus which has to be moved around, al-
uminium is rapidly coming into extensive use. Bicycles are
being made very successfully, notably by a St. Louis firm, who
harden the aluminium with copper and zinc, and cast it very
solidly under pressure. Their frames have stood even more
severe tests than steel ones, and yet have only one-half the
weight. Aluminium racing sulkies are used for fast running,
and two records, broken during 1894, were by horses carrying
aluminium shoes and pulling aluminium sulkies. One of these
is said to have weighed only 20 pounds entire. An aluminium
cab is running in Paris, and a railway carriage of this metal
will probably appear soon. In fact, many of the doors, sash-
frames, handles, racks, etc., formerly made of iron or brass,
have already been replaced by it.
If the problem of aerial navigation is ever satisfactorily
solved, we may expect to see aluminium largely employed in
constructing the machines. Professor Langley, at Washington,
and Maxim, in Great Britain, represent the utmost so far ac-
complished in this direction, and they use sheet and wire-rope
of aluminium.
WORKING IN ALUMINIUM. 479
Decorations. — The sulphurous acid of the air or of the pro-
ducts of combustion likewise leave aluminium untouched, while
they quickly blacken silver. This caused its early use for re-
flectors, for, while not taking at the start so high a polish as
silver, yet it keeps its lustre indefinitely ; it has also the added
superiority that its slight blue tint partly neutralizes the yellow
color of artificial light, thus reflecting a very soft, white light.
Even the unconsumed gas itself, containing sulphuretted hydro-
gen, does not blacken the aluminium reflector in the least. It
would follow that as a material for candelabra, chandeliers, or,
in general, for any objects exposed to the air in dwellings, alu-
minium keeps its color in a manner far superior to silver. This
explains the superiority of aluminium leaf to silver leaf for
almost any use, either for picture-frames or mural decorations
indoors, or for outside decorations, especially in large cities
where the air contains much sulphurous acid gas Since alu-
minium leaf can be purchased in books at as low a price as
silver leaf, it has entirely displaced the latter.
Some of the latest uses in this line are extending very rap-
idly, such as reflectors for locomotive headlights, in the ceilings
of public halls, and shades for incandescent electric lights. For
the first mentioned use it is vastly superior to the present nickel
reflectors, and the Philadelphia firm manufacturing them can
scarcely supply the demand.
Much of the fancy grill-work used for decorating desks,
shelves, stair-cases, elevator shafts and elevators themselves,
is being made in aluminium. It is strong enough for all such
purposes, and for the elevator car, which is lifted many thous-
ands of feet in a day, the saving in weight is of great advan-
tage.
Mine-work. — For underground work, aluminium possesses
great advantages over iron because of its non- rusting. Mine
cars and Hfting-cages are made of it to great advantage, because
every pound of dead weight saved on these allows so much
more coal or ore to be lifted by a given power. Aluminium
safety lamps are also a great improvement, not only from their
480 ALUMINIUM.
lightness but because the high conductivity of aluminium gauze
keeps the flame from passing through it so quickly as through
brass gauze. Several collieries around Essen, Germany, are
using these, as also aluminium lamps for the miners' hats.
Medicine. — The harmlessness (innocuousness) of aluminium
gives it exceptional advantages for use in surgery. M. Char-
ri^re made, in 1857, a small aluminium tube for a patient on
whom tracheotomy had been practiced. The tube was very
light, and, therefore of little inconvenience to carry, and after
wearing for some time the metal was very little attacked. After
a long time a very thin, almost invisible coat of alumina formed,
which was absolutely without harmful "efifect on the patient.
Under the same circumstances a silver tube would have been
blackened and corroded by the purulent matter. Aluminium
has been used very advantageously for suture wire, and we can
also deduce from this the great advantage there would be in
making various surgical instruments of this material, not only
from their not being corroded, but also because of the decrease
in weight of the instrument case which the physician has to
carry, often for long distances. We would also notice the com-
fort to be derived from this large decrease of weight in any §ort
of surgical appliances, braces, trusses, etc., which have to be
worn and carried about continually on the person.
Dental plates have been cast of aluminium, and, when com-
plete, their weight is only a fraction of that of gold plates. But
two difficulties are met in this application ; aluminium contracts
very much in solidifying, and it is found almost impossible to
cast it solidly on to the teeth ; also, pure aluminium is slightly
corroded by the acids of the food and the saliva. To overcome
these difficulties. Dr. Carroll (see also p. 446) adds a little
copper, which he says decreases the contraction so much that
the teeth remain solidly imbedded in the plate ; while the addi-
tion of some platinum and gold renders it unalterable in the
mouth. The aluminium plates possess the added advantage
that on contact with metallic substances no disagreeable electric
current is set up. It is a matter of common experience that if
WORKING IN ALtlMINIUM. 481
a bit of iron, e. g., a carpet tack, is held in the mouth and
touches a gold plate, a disagreeable bitter sensation is at once
felt, due to electro-magnetic action. For this reason, some
persons even refuse to wear the gold plates ; but it is stated by
those who have worn aluminium plates that no such effect oc-
curs with this metal. Further, broken teeth, etc., can be
again attached by means of rubber cement, the sulphur of the
rubber having no action on the aluminium.
Dr. Fowler* obtained a patent for using aluminium in den-
tistry in combination with vulcanite, which consisted in mixing
granulated aluminium with a vulcanizable compound and then
vulcanizing in the usual manner. The patent also claimed the
inlaying of vulcanite articles with aluminium, the joining of
articles made of vulcanite or rubber with clasps or rivets of alu-
minium, and the use of aluminium tacks, nails, etc., in making
rubber shoes.
Scientific Instruments. — We have long been familiar with the
appearance and advantages of the aluminium opera and field
glasses, but the difiSculties met in working the metal, and more
especially the monopoly of their manufacture by a few firms,
have kept the price of these desirable instruments at unreason-
able figures. Since there are but a few ounces of aluminium in
the frames of these glasses, there is no reason at all why pur-
chasers should have to pay double price for aluminium mount-
ings over those of other metals ; and with the present wide de-
velopment of the employment of aluminium I hope it will not
be long before some enterprising American firm will make
these instruments and sell them more nearly at their proper
cost. Long before i860, Loiseau, of Paris, made for Captain
Gordon a beautiful sextant, which only weighed one- third as
much as those ordinarily made of brass. For an instrument
which one is obliged to hold to the eye by one hand for several
minutes, making observations from the rolling deck of a vessel,
this property is of the greatest convenience, as any one will at-
*U. S. Patent, 46230, Feb. 7, 1865.
31
482 ALUMINIUM.
test who has had his wrist ache after making the noon observa-
tion. Similarly, a difference of a pound in the weight of a
tourist's glass may hardly seem much on lifting the glass, but
we have trustworthy witnesses who say that it makes twenty
pounds difference towards the end of a long walk. I suppose
that sextants have not been more generally made of aluminium
because of its high price ; this is now much less of an obstacle
than formerly, and it is to be hoped that the instrument-makers
will take up this subject again with fresh vigor. Engineering
instruments, as transits, levels, etc., are made with aluminium
frames, but it is certain that they have not come as yet into
anything like common use. With cheaper aluminium it is to
be hoped that the makers of these instruments will lighten the
burdens of our surveyors by bringing about their general
adoption.
For any scientific instrument where the inertia of a heavy
moving part is to be avoided, aluminium is the material par
excellence. For electrical instruments it has the additional
advantage that it is absolutely without magnetism or polarity,
if pure, and it thus makes the most suitable material for com-
pass boxes, galvanometer cases, etc.
Aluminium is used for the beams of fine chemical balances
as well as for the very small weights used with them. The
aluminium weights for this purpose are in general use; they
are quite rigid, unattacked by the air, and the smallest weights
are of such size as to be quite manageable. The 50 milli-
gramme weight can still be formed into a cylinder and termi-
nated with a button, while the tenth of a milligramme is suffi-
ciently large to be easily handled. The only other metal used
for these small weights is platinum, and when the same weights
in each metal are placed side by side the difference in size is
very striking. Aluminium balances are now frequently seen.
CoUot Bros., of Paris, made a balance which, with the excep-
tion of the aqua-marine bearings, was composed entirely of alu-
minium. Pure alunjinium, however, is hardly rigid enough
for the beams, and'Sartorius, of Gottingen, was the first to
WORKING IN ALUMINIUM. 483
Stiffen these by adding 4 per cent, of silver. With this im-
provement an aluminium balance has no equal. They are now
made by almost all the fine-scale-makers. Troemner, of Phila-
delphia, places aluminium beams on all his assayers' button
balances, while his analytical balance, entirely of aluminium
except the bearings, is pronounced the chef d'oeuvre of the
scale-makers' art. Dr. A. A. Blair, the noted analytical
chemist, after using one for several years, states that for sen-
sitiveness and quickness it is unsurpassed, while the gases of
the laboratory have not had the slightest effect on it. The
same rnaker constructs large bullion balances of the same
material.
Coinage* — Aluminium has been repeatedly proposed as a
material for coins. As far back as 1856 Henri Montucci, a
member of the French Academy, proposed this use to the
Emperor. It then combined high price with lightness, and if
it had always kept that high value it might have been substi-
tuted for silver. But what a mistake it would have been ! A
single invention, which reduced the price of aluminium one-
half, would have depreciated the value of this currency to the
same extent. The matter is different now, for two reasons ;
first, the price of aluminium is so low that future reductions
can only be by cents per pound ; second, as aluminium is so
cheap it is out of question that it be used for money of final re-
demption, but this same fact brings it into direct competition
with nickel and bronze for minor coinage.
Granted that aluminium can be suitably hardened by adding
a few per cent, of some other metal, and there is not a single
requirement for a metal for coinage which- such an alloy does
not possess. For instance, the conditions to be filled are :
1. Capability of being cast, rolled, punched, stamped, and
taking a fine impression. Aluminium does this as well as any
metal known.
2. Durability. Aluminium is a very smooth metal, possess-
' * Further information than given here may be found in an article by the writer in
the "Aluminium World," January, February and March, 1895.
484 ALUMINIUM.
ing a sort of inherent, anti-friction quality, and even the pure
metal, hardened by stamping, wears remarkably well.
3. Non-corrosion. Aluminium resists corrosion better than
copper, bronze or any of the base metals. In addition to this
is the fact that if it does corrode slightly, the salts formed are
entirely harmless. No other metal compares with it in this
regard.
4. Cheapness. Since small coins are only of nominal value,
it becomes a matter of profit to the government to make the
coin as cheap as it can. But aluminium ingot at $0.50 per
pound is equivalent for coining purposes to nickel alloy at
$0.14 and bronze at the same figure. But these really cost
$0.20 and $0.10 respectively, so that aluminium would cost
slightly more -than one and less than the other. It is therefore
clearly suitable in this respect.
5. Large supply. If all the nickel and copper coins in the
United States were replaced by aluminium, the annual amount
required would be about one hundred tons. This is only ten
per cent, of the total amount which will be produced this year.
When nickel was adopted for coinage the supply of it was rela-
tively much less abundant.
6. Difficult to counterfeit. Of all ordinary metals, aluminium
would be the hardest to counterfeit. Further, the inducement
to try to counterfeit minor coin is much less than with larger
money, and this condition is not of as great relative importaftce.
7. Lightness. The people of the United States are carrying
around probably 3,000 tons of minor coins. If this could be
made 2,000 tons less, who would not favor an immediate change ?
Granted, therefore, that aluminium can be suitably hardened,
there is not a single requirement in which it is not equal to the
metals now in use for minor coin, and in two ways it is far su-
perior to them, viz., innocuousness, cleanliness and lightness.
It is to be hoped that the United States government will rec-
ognize the advantages of such a change and lead the world in
making its minor coinage of aluminium.
Chemical Apparatus. — Dr. George Bornemann has critically
WORKING IN ALUMINIUM. 485
tested some aluminium utensils made by Max Kaehler and
Martini of Berlin, and reports as follows:* An aluminium
hot-air oven is heated quicker and to a higher temperature
than a copper one; the distribution of temperature is more
even ; no chemical alteration after daily use for ten months.
Water baths evaporate water very quickly, and one tested suf-
fered no loss in weight or disfiguration in three weeks' use.
Rings and pincers stay bright; lacquering is unnecessary.
Sand baths remain unaltered in weight, but care must be taken
not to overheat them. Stove-pipe, tripods and hot funnels are
very desirable. Crucibles are not to be recommended, as they
cannot be used above incipient redness.
Several chemical companies are using aluminium stills, evap-
orating dishes, etc., particularly in the manufacture of medi-
cinal extracts, etc., with great satisfaction.
Culinary Utensils. — No less than six large firms are at pres-
ent making aluminium cooking utensils in the United States.
The pioneer was the Illinois Pure Aluminium Company, at La-
mont, Illinois, whose factory was put in operation early in 1893.
For about a year, the success of the venture was uncertain, but
everyone who used the utensils recommended them so highly
ithat the trade then began to grow, and at present the supply is
not equal to the demand. America has certainly taken the
lead in this application of aluminium, which, it is the writer's
firm opinion, will overshadow in magnitude all other applica-
tions of the metal.
The well-established advantages of these utensils are :
1. Non-poisonous. This cannot be said of any other uten-
sils except the expensive and fragile enamel-lined vessels.
2. Easily cleaned. It is very seldom that anything burns
fast or sticks to an aluminium utensil. If such does happen, a
soaking in water removes it entirely.
3. Not corroded. None of the acids found in foods have
any perceptible corrosive action on aluminium. Daily use for
*Chemiket Zeitung, January 11, 1893, p. 34.
486 ALUMINIUM.
three years, in every way, has left no signs of corrosion on a
utensil in use at the writer's home. In weight, the utensil has
lost one-quarter of an ounce, which would point to about a
hundred years as the probable time it will take to wear out.
4. Do not scorch. It is a singular fact, that it is almost im-
possible to scorch even the most delicate foods in an aluminium
vessel. This is a well-attested fact, and is due to the great heat
conductivity of aluminium preventing a high local temperature
at any one spot. On this account aluminium is not well- suited
for frying-pans or skillets, in which the object is to brown the
food, that is, to superficially scorch it in a measure.
5. Cook quickly. Kettles and sauce-pans have their contents
heated very quickly, because of the great facility with which the
metal conducts heat.
6. Lightness. Only one-third that of other utensils.
7. Durability. Do not corrode, and show very little wear
outside; besides, there is nothing to crack off, as in enamel
wear, no coating to wear through, as in tinned wear, and it will
not crack like cast-iron ware. The utensils, if properly treated,
are almost indestructable and will wear almost indefinitely.
I have no hesitation in predicting that when the general pub-
lic have proven by actual experience the merits of these uten-
sils, they will displace all other kinds in the kitchens of all ex-
cept the poorest classes. Already, they are being largely used
in hotels, restaurants, railway cars, steamships, large institutions,
and by makers of preserved food and confectionery. Several
makers of pickles, condiments and soups have adopted them.
For such use on a large scale, the kettles are made with a
double bottom and are heated by steam.
Table Ware. — The writer does not recommend aluminium
for use on the table for such articles as are subject to consider-
able wear. Spoons, knives, forks and plates, especially, very
quickly lose their high polish, and become dull. However, for
articles which do not meet heavy wear, its use is advantageous.
Especially is this the case with soup-tureens, vegetable and
meat covers and dishes, in which the property of aluminium of
WORKING IN ALUMINIUM. 487
keeping hot a long time is of the greatest advantage. Alu-
minium chafing-dishes are also highly recommended. For
sugar bowls, cream and water pitchers and trays, aluminium
does very well, its particular advantage over silver-plate in these
cases being that it does not blacken. Every housekeeper knows
what an amount of cleaning and polishing this saves. Whole
services of plate have been made in aluminium.
Constructions. — For purposes of construction, aluminium
cannot replace steel, except where expense is a secondary con-
sideration, and lightness or resistance to oxidation are the first
conditions to be filled. If in a machine a certain moving part
must be as light as possible, that piece may be made of alumin-
ium, while the rest is still of iron or steel. In torpedo boats,
railway carriages, cabs, wheel-barrows, or- any apparatus which
is moved around continually, lightness is a prime consideration,
and the substitution of aluminium for steel is simply a question
as to whether the lightness gained compensates for the in-
creased cost. For a stationary structure, the question is sim-
ply one of the minimum cost for a given strength, and in such
fields steel is king, and will stay at the head until aluminium
can compete with it in price, bulk for bulk, which is a very re-
mote contingency.
It was said that a 16-story buildiflg in Chicago was to be
built of iron frames with plates of aluminium fastened on for a
facing. These plates were to be 36 inches by 20 inches, and
three-sixteenths of an inch thick, composed of an alloy of 90
per cent, aluminium and 10 per cent, of copper. The informa-
tion, however, was partially misleading ; the alloy used was alu-
minium bronze, 90 per cent, copper and 10 per cent alumin-
ium.
Batteries. — Since aluminium is so inert in presence of nitric
acid, it forms a good substitute for platinum in the Grove bat-
tery. Hulot used a couple composed of an aluminium plate
and a zinc plate amalgamated for some time previous to use.
The exciting fluid may be either dilute nitric or sulphuric acid.
With water, charged with one twentieth part of sulphuric acid
488 ALUMINIUM.
at 66°, the cell gave for some hours a current at least equal to
that afforded by platinum in the same conditions. After six
hours its original force was diminished one-fifth, and at the end
of 24 hours the cell was not entirely polarized, but still gave
one-fourth its original current. To restore the electro-negative
character of the aluminium it was only necessary to immerse it
an instant in nitric acid and wash well. Col. Frishmuth, of
Philadelphia, used aluminium-zinc batteries for several years
in electrolytic experiments as well as for ordinary house use,
and has stated that it answered as well as platinum, and in
some cases gave greater power.
From experiments made by the writer (p. 91), it appears
that the purer aluminium is, the more it resists nitric acid. It
is therefore recommended to make battery plates out of the
purest obtainable aluminium, and on no account to use an
alloy.
Lithographic Plates. — Aluminium is being successfully used
to replace the expensive Solenhofen lithographic stone. One
inventor gives the directions for using it as follows :* "The
plates are cleaned, levelled and polished, and then prepared for
printing in one of two ways. One way is to apply "transfers"
in chalk or ink to the plates, on which " facings " are then pro-
duced by the action of suitable acids. Or, the plates may be
first treated with the acids until their surfaces have an opaque
white appearance, then, after rinsing with a solution of alum or
of acetic acid to enable the plates to take them, "transfers"
are applied and the plates then subjected to a second treatment
with acid, this time more concentrated than before. Acids
suitable for this purpose are ortho-, meta- or pyro-phosphoric,
or hydrofluoric. These acids form salts of aluminium which
are insoluble in water, and which, while attached to the plates;
retain enough water to prevent the adherence to the parts acted
on of the oily inks employed for coloring the other parts of the
plates. An acid mixture such as is used in the process is com-
* English Patent 16,312; Sept. 12, 1892. O. C. Strecker. Mainz, Germany.
WORKING IN ALUMINIUM. 489
posed, for example, of 10 parts of a. solution of gum, 3 of a
saturated solution of gallic acid, and i of a 20 per cent, solu-
tion of ortho-phosphoric acid.
Krebs, of Frankfort, recommends sponging the polished sur-
face with a dilute solution of caustic soda, and in order that
the surface shall take the ink it is covered with a varnish com-
posed of zinc white, potash and saltpetre moistened with
alcohol.
The Ellery-Howard Co. of New York are using aluminium
plates for printing, and report them entirely satisfactory.
Flash-light Powder. — Very fine aluminium filings, or alumin-
ium powder made by grinding up the leaf, makes an excellent
flash-light for photographic purposes. Its advantages over
magnesium are that it is cheaper, not so liable to explode in
preparation, and produces none of the white fumes so disa-
greeable when using magnesium. Villon, the first to use it,
recommends the three following mixtures:*
I. II. III.
Aluminium powder 8 10 10
Chlorate of potash 20 25 25
Sugar 2 — 2
Nitrate of potash — S —
Potassium f erro-cyanide — — 3
Sulphide of antimony — 4 —
These powders may be ignited in various ways, but the best
and safest is to project them into the flame. The following
mixture also gives a very intense light :
Aluminium powder 20 parjs,
Lycopodium 5
Nitrate of ammonia - i "
Villon recommends using a lamp fed in its centre with a jet
of oxygen.
Mr. Alexander Black, of New York, recommends the follow-
ing mixture for very rapid flashes :
* Reveu de Chimie Industrielle, 1892.
490 ALUMINIUM.
Aluminium powder 5 parts.
Chlorate of potash 15 "
Sulphide of antimony 3 "
The London Lancet recommends for medical photography,
laryngoscopic, auroscopic and other demonstrations, the burn-
ing of a thin aluminium ribbon in an ordinary spirit-lamp or
blow-pipe flame.
Miscellaneous. — We can do no more than mention the vari-
ous other uses to which aluminium has been put.
Cash registers and conveyers.
Watch and key chain. Dog chains.
Horse-shoes, bits, bridles, stirrups, harness trappings.
Insoles for shoes, to keep out dampness. Shoe horns.
Surgical instruments, suture wire, tracheotomy tubes.
Braces, trusses, supports for various parts of the body.
Fine wire woven into passementerie, uniforms and flags.
Metallic parts of trunks and traveling bags.
Keys — hardened by drop-forging cold.
Watches, compasses, knife-handles.
Cases for cigars, cigarettes, matches, spectacles.
Teething plates for infants.
Artificial limbs and noses.
Pen and pencil holders. Slate pencils. Paper cutters.
Thimbles.
Pocket rules, scales, levels.
Toilet articles, backs of brushes, combs, etc.
Walking sticks, umbrella frames, billiard cues.
Picture frames, mirror frames, placques for hand-painting.
Pufif boxes, collar and cufif boxes, perfume bottles.
Hat pins, hair-pins, bracelets, brooches, rings, etc.
Candlesticks, fancy baskets, card receivers, ink-stands.
Cigar-holders and pipes, with amber mouthpieces.
Moulds for forming cigars.
Patterns and models for metal castings.
Eye-glass frames and chains.
Name-tags on flying pigeons.
WORKING IN ALUMINIUM. 49 1
Boot-trees and lasts in shoe factories.
Connections in rubber hose, clasps on rubber garments.
Blades for ventilating fans, especially those run by electric
motors.
Business and visiting cards.
Body of ice and roller skates.
Photographic cameras, tripods, " kodaks."
Padlocks, especially for portable use.
Car roofs, railway semaphore signals.
Shelves on which to evaporate fruit.
Musical instruments, cornets, trombones, horns, drum frames.
CHAPTER XIV.
ALLOYS OF ALUMINIUM.
Aluminium unites easily with most of the metals, the com-
bination being usually accompanied by a disengagement of
heat, which is particularly active in the case of copper. (I do
not know that any attempt has been made to measure this heat
quantity except in the case of iron). This circumstance is
taken to be an indication that these alloys are chemical
combinations of the metals rather than mere mechanical mix-
tures. Lead and antimony appear to be the only metals not
alloying with it easily. The practical production of these alloys
from the metals is in general a very easy operation. The alu-
minium may be melted in a carbon or magnesia-lined cru-
cible, without a flux, and the other metal simply thrown in;
it falls to the bottom, melts, and is absorbed by the aluminium.
In some few cases the alloying metal must be mixed in pow-
der with finely-divided aluminium and heated together in a
closed crucible, but this is only exceptionally the case. Again,
a bar of aluminium may be taken in the tongs and held under
the surface of another metal already melted. This is the best
method of introducing small percentages of aluminium into
other metals, unless we may except the adding of a small quan-
tity of rich alloy to pure metal, thus diluting the percentage of
aluminium to the desired quantity. Most of the alloys thus
produced are improved by careful remelting, the aluminium
seeming to become more intimately combined. The alloy made
in the first operation is often not entirely homogeneous, but be-
comes more uniform, and finally perfectly so, by repeated
fusions. Very few of the alloys will Hquate; in general the
alloy acts as a single metal. However, in some cases where
(492)
ALLOYS OF ALUMINIUM. 493
the alloy is not of a very definite or certain composition, a li-
quation may take place, leaving as a residue an alloy with dif-
ferent proportions from the fluid metal running off. In the
case of volatile metals, they can usually be driven out of the
aluminium by keeping the alloy melted and exposed to a heat
sufficient to drive off the volatile metal.
The useful alloys of aluminium seem to fall naturally into
two groups: i. Aluminium containing not over 10 to 25 per
per cent, of other metals; 2. Other metals containing not over
10 to 15 per cent, of aluminium. In almost every case, alloys
between these limits possess no useful properties, and are mere
chemical curiosities.
I . Aluminium is too soft to stand much wear, or to keep a
high polish, and too weak to support much stress. In order,
then, to make it harder, stronger and better wearing, and at the
same time to keep its valuable lightness and beautiful color, it
is alloyed with a small percentage of some suitable metal.
Silver, nickel, copper or tin is frequently used for this purpose,
as well as some other metals, as will be explained at length in
the succeeding consideration of the alloys. It might here be
remarked that the color of aluminium is not radically altered,
except by very large proportions of the foreign metal, by
reason doubtless of our proportions being expressed by weights,
while the influence of a metal in changing the color of another
depends more on its volume. For instance, an alloy of 50 per
cent, aluminium and 50 per cent, copper has the color of alu-
minium, an alloy with 70 per cent, of copper still has the white
color of aluminium, but with 85-95 P^r cent, of copper the
alloy is yellow. It has experimentally been observed that the
color appears to change from white to yellow at about 82 per
cent, of copper. If we combine equal volumes of copper and
aluminium, our alloy would contain about 77.5 per cent, of
copper. If then, we acknowledge the principle that the metals
affect each other's color according to the proportions by volume
in which they combine, we see the explanation of both facts —
the very small influence of foreign metals in changing the color
494 ALUMINIUM.
of aluminium, and the great influence aluminium has in whiten-
ing or changing the color of other metals. Again, precisely
the same principle holds when we consider the specific gravity
of these alloys, except that in this case our fundamental pro-
position— that the metals afifect each other's specific gravity
according to the proportions by volume in which they com-
bine— is capable of mathematical demonstration. But we have
also to consider in the case of the specific gravity a most
curious phenomenon, which is, that aluminium seems to be
able to absorb several per cent, of certain metals without in-
creasing in volume, and, in some cases, it even decreases in
volume. The basis for this statement is easily recognized. For
instance, some aluminium was cast in a mould which gave a
piece of a certain size weighing 480 grains. The aluminium
was melted and 5 per cent, of silver added to it ; a piece was
then cast in the same mould. Now, if the aluminium had ab-
sorbed the silver without increasing in volume, the second test
piece should have weighed 504 grains ; it weighed 502 grains,
showing only the merpst dilatation of the aluminium in absorb-
ing 5 per cent, of silver. So, if we calculate from the analyses
of commercial aluminium given in Chapter III., the specific
gravity of the alloy (for we can so consider it), on the suppo-
sition that all the foreign elements are absorbed by the alumin-
ium without change of volume, it will be found that in almost
every case this calculated specific gravity is very close to or
even below the observed gravity, showing in the latter event
that even a condensation beyond the volume of the aluminium
had taken place. This condensation seems to offer a natural
explanation of the hardening and strengthening effect produced
by the addition of a small quantity of the metals named.
2. At the other extreme of the scale of alloys we have those
containing a few per cent, of aluminium. In general, the effect
of a small quantity seems to be principally a notable increase
in strength and a striking change in color of the highly colored
metals. A very small quantity has little effect in reducing the
specific gravity, but as the quantity increases, the effect is what
ALLOYS OF ALUMINIUM. 495
we would infer from the previous remarks on specific gravity.
The reason of this is that the condensation in alloying taking
place with these alloys is so great that the metal absorbs the
aluminium without any noticeable increase of volume, and its
specific gravity may be even increased slightly at first. This
great condensation offers a partial explanation of the strength-
ening of the original metal, since its texture is finer and its
hardness increased. After a certain small limit in the percent-
age of aluminium is passed, the beneficial effects alluded to are
overpowered by the influence of crystalline chemical combina-
tions between the alloying metals, and the alloy quickly loses
strength and malleability. With the exception of copper and
tin, 5 per cent of aluminium is the limit of the useful alloys at
this end of the scale.
The alloys of aluminium with copper and iron have become
so important that it seems proper to devote separate chapters
to their consideration ; the remainder of this one will therefore
treat of the alloys with metals other than copper and iron. I
wish to remark, that as the tertiary alloys cannot be rigorously
classified, we will have to place them under the alloys of that
metal which, besides aluminium, seems to be their character-
istic ingredient. Some of the combinations of aluminium with
metalloidal elements, which might possibly be looked for in
this chapter, are described in Chapter V. among the compounds
of aluminium.
Aluminium and Antimony.
Tissier Bros, state that they were unable to get a homogene-
ous alloy of these two metals.
Dr. C. R. A. Wright * concluded that there is no commercially
valuable alloy of these two metals. He found that when alu-
minium is melted in a crucible and lumps of antimony dropped
in, they fall to the bottom and melt quickly. The two metals
remain separate until stirred, when part of them unite to an
alloy which immediately solidifies because of its high melting
♦Journal of the Soc. of Chemical Industry, June, 18912.
496 ALUMINIUM.
point, while the remainder stays as a fusible alloy of much lower
melting point. This solidified alloy has the composition
AlSb (81.6 per cent, of antimony), is a gray mass with an iri-
descent lustre, and does not melt below 1000° C, which is most
remarkable, considering that the melting points of its in-
gredients are 625° and 425° respectively. The alloys low in
aluminium look like antimony, those low in antimony are some-
what spongy, and they all slowly disintegrate in the air and
disengage hydrogen in water.
Roche * arrives at somewhat different results. He confirms
the existence of the alloy AlSb, with its abnormally high melt-
ing point, but he claims that aluminium containing less than 5
per cent, of antimony *is malleable, and superior in hardness,
tenacity and elasticity to pure aluminium. Above this, the
hardness and tenacity diminish, until at 10 per cent, antimony
the alloy crystallizes in brilliant laminae. The melting point
and ease with which moist air attacks the alloy increase up to
81.6 per cent, of antimony (AlSb), which in moist air or water
crumbles to a black powder. Roche recommends these alloys
as forming, when melted with other metals, as copper or nickel,
alloys of great hardness, strength and elasticity^
t Hoeveler states that he has tried to get Roche's alloys, but
with negative results. In no way could he get homogeneous
alloys with 6 or 12 per cent, of antimony; even a little antimony
makes the aluminium weak and brittle.
The only useful alloy claimed by Roche is the one with less
than 5 per cent, of antimony. This, it is true, can be made
apparently quite homogeneous, casts and rolls perfectly, and is
apparently superior in many ways to pure aluminium, as re-
marked by Roche. But, after a few months' standing, it will
be found that the alloy has disintegrated to such an extent as
to be worthless, a point which has probably been discovered
by this time.
* Moniteur Scientifique, 1893, p. 269.
tChemiker Zeitung, July 12, 1893.
alloys of aluminium. 497
Aluminium and Arsenic.
Wohler* stated that when these two metals were mixed inti-
mately and heated together they combine with a flame, forming
a dark-gray metallic powder which smells a little of arsenu-
retted hydrogen. It slowly evolves that gas in cold water,
rapidly in hot.
H. N. Warrenf melted aluminium and dropped arsenic upon
it. He states that an alloy is thus formed, which is decom-
posed on raising the temperature; but if the aluminium is used
alloyed with another metal, a regulus results.
Aluminium and Bismuth.
These two metals combine easily, the alloys being very fus-
ible, unchanged in the air at ordinary temperatures, but oxid-
izing rapidly when melted. As small a quantity of bismuth as
O.i per cent, in aluminium makes it so brittle that it will crack
under the hammer in spite of repeated annealings. Tissier
Bros, tried 0.5, 2.5, 3 and 5 per cent, of bismuth, but with simi-
lar results; with 10 per cent, of bismuth, however, the alloy was
not so brittle and could be worked under the hammer to a cer-
tain extent, but could not be rolled or drawn. It takes a fine
polish and is not attacked by nitric acid or blackened by sul-
phuretted hydrogen. The same chemists found that on melt-
ing I part aluminium with 2 parts of bismuth they obtained in
the crucible an alloy of the two metals floating on top of pure
bismuth. The alloy contained approximately 75 per cent, of
aluminium, showing that aluminium does not appear to be able
to take up over 25 per cent, of bismuth. This alloy was not so
brittle as pure bismuth, and was so distinct from it in the cru-
cible that the two layers could be separated by a blow of the
hammer.
Aluminium and Boron.
Deville obtained an alloy rich in boron by melting aluminium
* Pogg. Ann., 1827, ii. 160.
t Chemical News, Aug. i, 1890.
32
498 ALUMINIUM.
with borax, boracic acid or fluo-borate of potassium. The
alloy is very white, only able to bear slight bending and splits
in the rolls. It exhales a strong odor of hydrogen silicide, due
to its having absorbed silicon from the vessel in which it was
prepared. Metallic boron may be easily extracted from the
alloy as both graphitic and diamantine boron. (See also
Chapter V.)
H. N. Warren introduced aluminium into a molten mixture
of fluor-spar and vitrified boric anhydride which had been
heated in an oxy-hydrogen furnace until fumes of boron flu-
oride appeared. The aluminium immediately set free boron,
which dissolved in the aluminium in excess, rendering it crys-
talline and brittle. The boron thus dissolved is in the graph-
itoidal state.
Aluminium and Cadmium.
Cadmium unites easily with aluminium, producing alloys
which are malleable and easily fusible, and which have been
used for soldering aluminium, but only answered that purpose
imperfectly. I have not found in any aluminium solder I have
tried any advantage gained by replacing zinc by cadmium.
C. R. A. Wright melted together equal parts of aluminium
and cadmium, and states that on keeping the mixture some
time about iOO° C. above the melting point of cadmium it sepa-
rated into two distinct layers, the upper part of which con-
tained 3.39 per cent, of cadmium, while the lower part con-
tained only 0.22 per cent, of aluminium. The addition of tin
prevented the separation and formed a strong ternary alloy.
Aluminium and Calcium.
Wohler states that an alloy of these metals was obtained by
fusing together equal parts of aluminium and sodium with a
large excess of calcium chloride. The alloy produced had a
lead color, easy cleavage, specific gravity 2.57, and was unal-
terable in air or water. Analysis showed it to be evidently a
mixture, as it eontained —
ALLOYS OF ALUMINIUM. 499
Aluminium 88.0 per cent.
Calcium g g <<
Iron 2.0 "
Prof. Mabery describes a peculiar product formed in the elec-
tric furnace, consisting principally of aluminium, copper, and
up to 3 per cent, of calcium (p. 343).
Aluminium and Chromium.
Wohler* heated violet chromium chloride with aluminium
wire, obtaining an alloy of the two metals, while aluminium
chloride volatilized. When i part of aluminium was used to 2
of the salt, a gray, crystalline mass resulted, from which excess
of aluminium was removed by caustic soda, leaving lustrous,
tin-white crystals. When these were heated in the air they be-
came steel-gray, but did not oxidize further. They were unat-
tacked by caustic soda or concentrated nitric acid, but dissolved
in hydrochloric acid, with separation of a little silica. Concen-
trated sulphuric acid oxidized them to a green mass. They
were fusible only at a very high temperature. On analysis,
this alloy was found to contain both iron and silicon, coming
from the aluminium used. Taking these out, the composition,
as regards aluminium and chromium, was —
CalculateJ'for AlCr.
Aluminium 31.6 33.92
Chromium 68.4 66.08
loo.o 100.00
Professor J. W. Langley has alloyed chromium with alumin-
ium by dissolving chromium oxide in a bath composed of fused
fluorides of aluminium, sodium and calcium, then stirring in
metallic aluminium. The latter reduces the chromium oxide,
passing into the bath as alumina, while the chromium alloys
with the excess of aluminium. It is found that 2 or 3 per cent.
of chromium makes the aluminium harder, denser and stronger
but decreases the malleability. Over 5 per cent, makes an
alloy which is almost unworkable.
" Ann. der Chemie und Pharmacie, 106, 118.
500 ALUMINIUM.
Lejeal produced by Wohler's method an alloy with 1 1 per
cent, of chromium. It was very brittle, crystalline and impos-
sible to work. It was necessary to dilute to below 3.5 per
cent, before the alloy could be hammered or rolled, and this
metal was criqu^ (crickly) after rolling hard. With this per-
centage, the fracture is crystalline, seggregated in the centre,
and gives a tensile strength, annealed, of 12.5 kilos per square
millimetre (18,000 lbs. per sqr. inch) with an elongation of 7
to 12 per cent.
Aluminium and Cobalt.
The following alloys have been mentioned, but I know
nothing of their properties : —
Cobalt. Aluminium, Copper. Iron.
Sun bronze 40 to 60 10 30 to 40 —
Metalline 35 25 30 10
Lejeal made an alloy with 6 per cent, of cobalt. It was
rolled easily from 8 m. m. thickness down to 2 m. m. without
annealing, and gave a fracture which was dark and pretty uni-
form. An alloy with 3 per cent, of cobalt gave : —
Tensile Strength. Elongation.
2 2
Kilos per m, m. Lbs. per in. Per Cent.
Worked hard 22.0 31,000 4
Annealed 16.5 26,000 20
Aluminium and Copper.
(See Chapter XV.)
Aluminium and Gallium.
Lecoq de Boisbaudran has stated that alloys can be formed
by melting these metals together at dull redness. The alloys
thus obtained remain brilliant, and do not sensibly absorb the
oxygen of the air in their preparation. After cooling they are
solid but brittle, even when the excess of aluminium has raised
the melting point to incipient redness. They decompose water
ALLOYS OF ALUMINIUM. SOI
in the cold, but better at 40° C, with rise of temperature, evolu-
tion of hydrogen, and formation of a chocolate-brown powder,
which is ultimately resolved into white flakes of alumina.
Aluminium and Gold.
Tissier Bros, state that aluminium can contain as much as 10
per cent, of gold without its malleability or ductility being im-
paired. The alloy with 10 per cent, of gold can be forged at a
red heat as well as aluminium, is a little harder than aluminium
but polishes scarcely any better. ^ The color of the alloy is a
peculiar brownish tint. The alloy with 1 5 per cent, of gold can
no longer be forged. ,
The addition of a small amount of aluminium to gold quickly
takes away all its malleability. Ten per cent, of aluminium
makes a white, crystalline, brittle alloy ; five per cent, is said
to be extremely brittle, as much so as glass ; one per cent, gives
an alloy similar to the gold-silver alloy called by the jewelers
" green gold." It is very hard but still malleable. Professor
W. Chandler Roberts-Austin, in a lecture on the influence of
other metals on gold, stated that while a sample of pure gold
had a tensile strength of 7 tons per square inch with 25 per
cent, elongation, the addition of 0.186 per cent, of aluminium
increased its strength to 8.87 tons (26 per cent.), its elongation
remaining practically the same — 25.5 per cent.*
" Niirnberg gold " is an alloy used to make cheap imitation-
gold ware, resembling gold in color and not tarnishing in the
air. Its composition is said to be
Copper 90 per cent.
Gold zM "
Aluminium iVi.
G. F. Andrews f has made a large number of experiments
with reference to using aluminium in jewelry, and states that
♦Journal of the Society of Arts, vol. 36, p. 11 25.
t Journal American Chemical Society, July, 1894, p. 485,
502 ALUMINIUM.
the alloys with gold are of little practical use except for decora-
tive purposes. His results are as follows :
Per cent,
of Gold.
6 As white as aluminium but much more brittle.
10 Harder than aluminium, does not work well except at a high
temperature. Color light violet brown.
1 5 Slightly violet, although nearly white. A very soft, 6ne-grained
metal.
50 Beautiful violet color; very soft and spongy.
78 Color peculiar, between pink and violet; very brittle.
90 Pale violet.
94 Violet approaching pink again.
Alloys with very little aluminium leave a bright violet color on
the cupel, under the blowpipe. An alloy of 50 parts gold, 45
copper and 5 aluminium takes the color and polish of fourteen
carat gold, but easily tarnishes.
Roberts-Austen has found with a Le Chatelier pyrometer
that the alloy AuAlj, containing 22 per cent, of aluminium,
melts at 1065° C. to 1070° C, or 25° to 30° above gold itself.
Small amounts of aluminium, however, lower the melting point,
0.47 per cent., giving the alloy Aui,,,, Al, almost effacing the
melting point of the gold, making it pasty, the mass only be-
coming really solid at 900° C. Up to i per cent, of aluminiym
the melting point is lowered, over this it begins to rise.
Roberts-Austen also made a curious experiment, showing
the great heat of combination of gold and aluminium. Thirty
grammes of gold was melted in a crucible, and kept at 1155° C.
A piece of cold aluminium weighing 0.3 gramme was put in
and rapidly stirred. At first the temperature fell to 1045°,
then rose briskly to 1380°, which was 225° above the initial
temperature of the gold.
It is possible to calulate roughly the heat set free in this ex-
periment. Assuming the specific heat of gold in the molten
state to be 0.036, and of liquid aluminium 0.308, we have —
" ALLOYS IN ALUMINIUM. 503
Heat absorbed by the gold
30 X 225 X 0.036 = 243 gramme calories.
Heat absorbed by the liquid aluminium
0-3 X (1380—625) X 0.308 = 70 " "
Heat to liquefy the aluminium
0.3 X 258 = 77
Total 390 " "
This is equal to 1300 kilogramme calories per kilo of alumin-
ium, a quantity equal to nearly 20 per cent, of the heat of oxi-
dation of the aluminium, and suggests the query whether the
evolution of heat may not have been largely due to the oxida-
tion of the aluminium by oxygen dissolved in the molten gold.
A careful analysis of the alloy after the experiment would have
thrown light on this question.
Aluminium and Iron.
(See Chapter XVI.)
Aluminium and Lead.
'Deville remarked that these two metals had so little tendency
to combine that there may be recovered intact at the bottom of
an ingot of aluminium any small pieces of lead which may
accidentally have dropped into the metal. Later, however,
Deville remarked that M. Peligot was able to cupel buttons of
impure aluminium with lead, thereby purifying the metal, and
thought that an alloy may exist in certain proportions at the
temperature necessary fdr cupellation. It is well known that if
aluminium and lead are melted down together and cooled they
separate, the aluminium chilling first and floating on the fluid
lead. Mierzinski remarks that this property would render it
possible to use aluminium for de-silverizing bulhon, if its price
allowed.
I do not think that the separation is quite as absolute as is
indicated above. On melting the two metals together, they
separated, with a sharp line of demarkation, so that there ap-
peared to be no combination ; but the lead was hardly as blue
S04 ALUMINIUM.
as at first, and contained about ^ per cent, of aluminium, while
the aluminium had visibly deteriorated, was darker, more crys-
talline, heavier, and contained at least 5 per cent, of lead, a
test for which could easily be had before the blowpipe on char-
coal. A small percentage of lead appears to be very harmful
to aluminium.
Lejeal melted together lead and aluminium and allowed them
to cool slowly. There was almost complete separation of the
two metals, and analysis showed —
Upper part of ingot. Lower part of ingot.
Lead 9.78 per cent. 94.49 per cent.
Aluminium 90.22 " 5.51 "
If antimony is present, however, the lead can take up more
aluminium.
I. H. Johannes,* of Washington, has patented an alloy com-
posed of 15 parts of aluminium to 85 parts of lead and anti-
mony combined, but for what purpose he finds it suitable is not
stated, it is probably for type metal.
C. B. Millerf patents an anti-friction alloy of lead 320 parts;
antimony, 64; tin, 24; aluminium, 2.
T. MacKellarl patents a type metal consisting of lead 65
parts; antimony, 20; tin, 3.3; copper, 3.3; aluminium, 3.3.
Heycock and Neville state that a small quantity of alumin-
ium does not cause a fall in the melting point of lead, which
would show that no alloy is formed.
Aluminium and Magnesium.
Wohler § fused these two metals together in the proportions
represented by ALMg, forming an alloy with 69.2 per cent, of
aluminium. The product was a tin-white mass, very brittle,
igniting at a red heat and burning with a white flame similar to
*U. S. Patent 443,943; Dec. 30, 1890.
tU. S. Patent, 456,898; July 28, 1891.
JU. S. Patent, 463,427: Nov. II, 189 1.
§ Ann. der Chemie und Pharm. 138, p. 253.
ALLOYS OF ALUMINIUM. 505
magnesium alone. The alloy in the proportions MgaAl, con-
taining 36 per cent, of aluminium was malleable, but completely
destroyed by leaving in water for a day, without any evolution
of hydrogen. Both these mixtures appear to contain a com-
pound of definite composition, for when treated with a solution
of sal-ammoniac they disengaged hydrogen abundantly and de-
posited a brilliant, tin-white metallic powder. The solution
contained magnesium chloride, while the residue was rich in
aluminium and appeared to produce some aluminate of magne-
sium, which clouded the solution. The metallic residue was
washed with water, again treated with sal-ammoniac solution
and then with solution of caustic soda until it no longer evolved
hydrogen. This residue was about one-third the total alloy,
and was insoluble in both the above reagents. It burned with
brilliant sparks when thrown into a flame.
Aluminium and Manganese.
Michel* (a pupil of Wohler) obtained an alloy of these
metals by melting together —
Anhydrous manganous chloride 2 parts
Potassium and sodium chlorides 6 "
Aluminium 3 "
On treating the regulus with hydrochloric acid the excess of
aluminium was removed, leaving a dark-gray crystalline pow-
der. This was unattacked by concentrated sulphuric acid in
the cold, but dissolved on warming. Dilute caustic soda dis-
solved out the aluminium, leaving a residue of manganese. Its
specific gravity was 3.4, and analysis showed it to correspond
to the formula MnAL, containing 60 per cent, of aluminium.
Mr. A. H. Cowles manufactured an alloy for electrical pur
poses, consisting of manganese 18 parts, aluminium 1.2, siHcon
5, zinc 13, copper 67.5. It was said to have a tensile strength
of 35,000 pounds, with 20 per cent, elongation, and as its elec-
* Ann. 'der Cham, und Pharm, 115, 102.
506 ALUMINIUM.
trical resistance was greater than German-silver, it was especi-
ally recommended for rheostats.
The same inventor also patented the addition of manganese
to commercial aluminium up to five per cent, for hardening and
strengthening purposes.
Aluminium and Mercury.
It is not easy to understand why Deville said in his treatise,
" Mercury is not able to unite with aluminium. Experiments
of this nature which I have made myself, and which Mr. Wal-
laston has confirmed, proved it most clearly." Several years
ago, before reading anything about the failure of mercury to
unite with aluminium, I remember on taking a clean, bright
piece of aluminium foil, putting on it a small globule of mur-
cury and rubbing in hard with the finger, I felt the foil become
hot and a white powder appeared immediately. On rubbing
still more a hole was eaten through the foil. I concluded at
once that the mercury amalgamated the aluniinium and that
the latter when distributed through the amalgam was in such a
fine state of division that the air readily oxidized it, forming the
white powder. In looking up the literature on the subject the
following information has been collected: —
Cailletet* stated that aluminium could be amalgamated by
the action of ammonium or sodium amalgam in the presence of
water ; also when the aluminium is connected with the negative
pole of a voltaic battery and dipped into mercury overlaid with
acidulated water, or into a solution of mercuric nitrate. Tissier
confirmed the latter method, adding that if the aluminium foil
used is not very thick it becomes amalgamated throughout and
very brittle. Tissier also found that aluminium may be made
to unite with mercury merely by the intervention of a solution
of caustic potash or soda, without the intervention of a battery.
If the surface of the metal be well cleaned, or moistened with
the alkaline solution, it is immediately melted by the mercury,
and a shining amalgam forms on its surface.
* Comptes Rendus, 49, 56.
ALLOYS OF ALUMINIUM. 507
Joule* States that if a solution of an aluminium salt is elec-
trolyzed, using mercury as the negative pole, it will form an
amalgam with the aluminium set free. Since the amalgam de-
composes water, setting free hydrogen, it is probable that all
the aluminium deposited would be promptly oxidized.
Gmelinf states that potassium amalgam introduced into a
hole bored into a crystal of alum immediately acquires a rotary
motion, which lasts sometimes half an hour. At the same time,
it takes up a considerable quantity of aluminium and becomes
more viscid.
It is first stated in Watts' Dictionary (vol. viii.), that "alu-
minium oxidizes when its surface is simply rubbed with a piece
of soft leather impregnated with mercury; the rubbed surface
becomes warm in a few seconds, whitish excrescences appear
consisting of pure alumina." In Watts' Supplement I., the
best method of preparing the amalgam for use is stated to be
by heating the two metals together in a gas which does not act
on either of them. The operation is performed by placing a
piece of aluminium foil at the bottom of a thick-walled test-tube,
and pouring well-dried mercury on it, the tube haying been
previously drawn out at the middle to prevent the foil rising to
the surface. The air is then expelled by a stream of carbonic
acid gas and the tube is heated, without interrupting the current
of gas, till the metal is all dissolved.
J. B. Bailie | and C. Fery made a study of the production of
aluminium amalgam, using the method just described ; their re-
sults were as follows : " If aluminium foil is placed in a tube
with mercury, it oxidizes very rapidly, becoming heated, while
the mercury loses quickly its ordinary fluidity and becomes
covered with a layer of alumina. By constructing thin glass
tubes and filling them with known weights of aluminium and
mercury, in an atmosphere of carbonic acid gas, heating the
tubes on a sand bath, we verified these facts : —
* Chemical Gazette, 1850, p. 339.
t Gmelin's Hand Book, vi. 3.
t Ann. de Chim. et de Phys., 1889, p. 246.
508 ALUMINIUM.
" a. The amalgamation proceeds more rapidly the higher the
temperature ; at the boiling point of mercury the solution is
very active.
"3. The vapor of mercury does not attack aluminium; only
liquid mercury attacks it.
" c. The weight of aluminium dissolved is proportional to the
weight of mercury used, and reaches a certain maximum after
a given time.
"On cooling the bath of mercury obtained, it became evident
that the amalgam consisted of a definite compound of alumin-
ium and mercury dissolved in excess of mercury, for, on cool-
ing, a crystalline paste separates out, floating on the bath. This
paste was strained out, put in a covered crucible and heated in
a current of hydrogen gas. The mercury distilled, leaving ar-
borescent crystals of aluminium. We thus determined the
composition of this compound to be, in 3.181 grammes.
Mercury 2.902 grammes = 91.26 per cent.
Aluminium 0.279 " ^ 8.74 "
" Its formula is probably AlaHgs, which would require 8.26
per cent, of aluminium."
These investigators further noticed that if a leaf of aluminium
has been once attacked by mercury and afterwards exposed to
the air, it cannot be again attacked, since the layer of alumina
produced adheres so closely as to protect it perfectly. In
order to attack it again it is necessary to drive off all the mercury
by heat and remove the alumina by acid. A leaf may be com-
pletely dissolved in a current of mercury.
Properties of aluminium amalgam. — The aluminium in its
amalgam is very easily acted upon ; indeed, it behaves like a
metal of the alkaline earths. If let stand exposed to the air it
covers itself immediately with gelatinous, opalescent excres-
cences of pure hydrated alumina, exhibiting both in their form
and growth considerable resemblance to the so-called Pharaoh's
serpents. This hydrated alumina is perfectly soluble in acids
and alkalies. However, the coating protects the portion un-
ALLOYS OF ALUMINIUM. S09
derneath to some extent, so that it takes a long time, say 24
hours, for the mercury to free itself completely of aluminium.
If the mercury containing aluminium is heated and agitated in,
air, more or less anhydrous alumina is formed, colored reddish
from a little mercuric oxide, but all the aluminium is speedily
oxidized. Water is decomposed by it at ordinary temperatures,
hydrogen being liberated.
Acids attack the amalgam, dissolving the aluminium, even
nitric acid (which does not attack aluminium en masse) dissolv-
ing out the aluminium completely. Caustic potash acts simi-
larly, forming potassium aluminate.
Bailie and Fery determined also that if antimony amalgam is
mixed with aluminium amalgam, small crystals of antimony
form immediately on the surface ; later, the aluminium oxidizes
and a bath of mercury remains free from both metals. Lead
amalgam produces a similar effect, except that some lead re-
mains with the mercury. It is interesting to note that this is
quite similar to the action of lead on a molten alloy of alumin-
fiim and tin, the aluminium being driven out of combination.
Krauchkoll * states that if aluminium and iron together are
connected with the negative pole of a battery and dipped into
mercury covered with acidulated water, an amalgam of both
iron and aluminium is obtained, which oxidizes more slowly in
the air than aluminium amalgam.
Helbig finds that when metallic aluminium is moistened with
a solution of mercuric chloride, the white, hair-like formations
characteristic of the oxidation of the amalgam are quickly
formed. Even the dry salt will act similarly.
Aluminium and Molybdenum.
Molybdic acetate was dissolved in hydrofluoric acid, the so-
lution evaporated to dryness, and the residue mixed with
cryoHte, flux and aluminium, in the same proportions as given
for tungsten. Excess of aluminium was dissolved from the
* Journal de Physique, III., 139.
5IO ALUMINIUM.
product with caustic soda, and there remained a black, crystal-
line powder consisting of iron-gray rhombic prisms, soluble in
hot nitric or hydrochloric acid, and containing only aluminium
and molybdenum in proportions corresponding to the formula
Al*Mo. (Wohler).
Aluminium and Nickel.
Tissier: " An alloy with 50 per cent, of nickel was made by
melting together the metals in equal proportions under sodium
chloride ; the heat evolved was sufficient to raise the mass to
incandescence. This alloy remains pasty at the temperature
of melting copper. It is so brittle that it pulverizes under the
hammer. By melting proper proportions of this alloy with
more aluminium, an alloy with 25 per cent, nickel was pro-
duced. This is less fusible than aluminium, and as brittle as
the 50 per cent, alloy. By melting some 25 per cent, nickel
alloy with aluminium, a 5 per cent, nickel alloy was obtained.
This is much less brittle than the preceding, but is still very far
from being easy to work. From the 5 per cent, alloy one with
3 per cent, was made. With this amount of nickel the alumin-
ium acquired much hardness and rigidity, and was easy to
work. A curious fact with this alloy is that it may be melted
on a plate of aluminium, showing its fusing point to be less
than that of pure aluminium, the reverse effect to what irpn
produces, which if present in the same proportion would di-
minish the fusibility of the aluminium. To sum up, the action
of nickel on aluminium is mdch analogous to that of iron, for
nickel, like iron, produces crystalline alloys with aluminium,
but if employed with care it gives to it certain desirable quali-
ties, such as hardness, elasticity, etc."
Michel* melted together aluminium with nickel chloride, and
obtained an alloy with nearly 25 per cent, of nickel, which was
tin-white, crystalline, specific gravity 3.65, but too brittle to be
of any practical use.
*Ann. der Chem. und Pharm., 115, 102.
ALLOYS OF ALUMINIUM. 5 I I
Lejeal states that an alloy he prepared containing 4.5 per
cent, of nickel had a coarsely- crystalline fracture, was easily
worked, rolled well, but gave poor mechanical tests, as follows :
Tensile Strength. Elongation.
Kilos per mm.- Lbs per in.- Per Cent.
Forged cold and annealed. .. , 14.7 21,000 6.0
" at low red heat 16.0 22,800 5.5
" " weak cherry red 16.3 23,000 n.5
The Pittsburgh Reduction Company have recently com-
menced selling aluminium hardened by a small per centage of
nickel, made by adding nickel oxide directly to the bath in
which alumina is being electrolyzed. They claim for these al-
loys a tensile strength in castings of 25,000 to 30,000 pounds
per square inch and in rolled bars or plates of 45,000 to 50,000
pounds. A bar of this metal shown to the writer was certainly
very strong and possessed of great elasticity, suggesting its
probable use for light wagon or carriage springs.
These nickel alloys, however, do not resist corrosion as well
as some of the other light alloys.
Aluminium has been used in small amount in casting metal-
lic nickel, as it reduces the nickel oxide and allows the metal
to melt easier.
An alloy of nickel 40 parts; aluminium, 30; tin, 20, and
silver 10, has been named " roseine " and is recommended for
jewelry.
Aluminium-Nickel-Copper Alloys.
The following alloy has a beautiful white color and takes a
high polish. It resembles some of the finer grades of German
silver: —
Copper 7° parts-
Nickel 23 "
Aluminium 7 "
A similar alloy, but somewhat harder, is called Minargent.
It contains
512 ALUMINIUM.
Copper loo parts = 56.5 per cent.
Nickel 70 " =39.5 "
Antimony 5 " = 2.8 "
Aluminium 2 " ^ 1.2 "
To make this alloy, the directions are first to melt together the
copper, nickel and antimony, and then granulate the resulting
alloy in water. The dried granules are mixed with the alu-
minium and with 1.5 per cent, of a flux consisting of 2 parts
borax and i part fluorspar, and then remelted.
F. H. Sauvage states that the following alloy resembles pure
silver. He gives it the name Neogen: —
Copper 58 parts.
Zinc 27 "
Nickel 12 "
Tin 2 "
Bismuth 3^ "
Aluminium J^ "
P. Baudrin claims that the following alloy resembles silver
very closely in color, malleability, ring, and even specific
gravity: —
Copper 75 parts.
Nickel l6
Zinc 2y^ "
Tin...... 2% "
Cobalt 2 "
Iron ii^ "
Aluminium ^ "
Mr. Jas. Webster has patented the composition of several
bronzes containing nickel. Prof. Kirkaldy's tests on these
alloys, made by the "Webster Crown Metal Company," now
the " Aluminium Company, Limited," gave results from 82,000
to over 100,000 lbs. per square inch with 20 to 30 per cent,
elongation.
a)* Copper is melted and aluminium added to it until a ten
per cent, bronze is made. There is then added to it i to 6 per
cent, of an alloy, ready prepared, containing
* German Patent, 11,577.
ALLOYS OF ALUMINIUM. S13
Copper 20 parts.
Nickel 20 "
Tin 30 "
Aluminium 7 "
The alloy thus prepared would contain, as represented by the
two extremes,
I. II.
Copper 89.3 86.4 per cent.
Nickel. 0.3 1.4 "
Tin 0.4 2.0 "
Aluminium lo.o 10.2 "
b)* The two following alloys are prepared in the usual way,
under a flux consisting of equal parts of potassium and sodium
chlorides, and are cast into bars :
I. II.
Aluminium 15 parts. Nickel 17 parts.
Tin 85 " Copper 17 "
Tin 66 "
100 "
100 "
To make the bronzes, equal parts of these two alloys are
melted with copper ; the more of the alloys used the harder and
better the bronze. The best mixture is of
Copper 84 parts.
AlloyI 8 "
" II 8 "
100 "
The copper is first melted, then the alloys put in together and
stirred well. As iron is harmful to this bronze, the stirrer must
be of wood or clay. This alloy is suitable for art castings,
kitchen utensils, etc., or anywhere where durability, hardness,
malleability, polish and very slight oxidizability are required.
A cheaper and more common alloy may be made of
Copper 91 parts.
Alloy I 4 "
" II 5 "
♦German Patent, 28,117.
33
514 ALUMINIUM.
These two bronzes would contain centesimally
Rich alloy. Poorer alloy.
Copper 85.36 94.58
Tin 12.08 6.70
Nickel 1.36 3.85
Aluminium 1.20 0.60
c) * The following alloy is said to withstand oxidation well,
to have great tenacity, durability, capability to bear vibrations,
and to take a high polish. A preliminary alloy is made of
Copper 200 parts.
Tin 80 "
Bismuth 10 "
Aluminium 10 "
The alloy proper is-formed by melting together
Preliminary alloy 4^ parts.
Copper 164 "
Nickel 70 "
Zinc 6li^ "
The final composition would be by calculation
Copper 55-67
Nickel 23.33
Zinc 20.50
Tin 0.40
Bismuth 0.05
Aluminium 0.05
It will be noticed that this alloy contains the same ingredients
as Baudrin's alloy, though not in exactly the same proportions,
the principal change being that it contains more nickel and less
aluminium.
d) t Another alloy patented by Mr. Webster contains
* English Patent; J8320, June 23, 1886.
t United States Pat?pt, 377,918, Feb. 14, 1888.
ALLOYS OF ALUMINIUM. 515
Copper 53 parts = 51.0 per cent.
Nickel 22>^ " =21.6 "
Zinc 22 " =21.2 "
Tin 5 " = 4.8 "
Bismuth 3^ " ^ o_y «
Aluminium V •' ^ 0.7 "
1 00.0
" Lechesne " is an alloy not very different from some already
mentioned, said to be invented by M. Thirion, but the English
patent being taken out by the Societe Anonyme La Ferro-
Nickel, of Paris. The patent mentions two alloys, containing
I. II.
Copper 900 parts. 600 parts.
Nickel 100 " 400 "
Aluminium i^ " 1^ "
Which would give in per cents : —
I. II.
Copper 89.84 59.97
Nickel 9,98 39.98
Aluminium 0.18 0.05
100.00 100.00
The first of these alloys is the one to which the name
"Lechesne" appears to be given. In a description of the
manufacture of this alloy a French magazine states that the
nickel is first put into a crucible and melted, the copper stirred
in gradually, then the heat raised and the aluminium added.
The alloy is heated almost to boiling and cast very hot. It is
claimed that this alloy is equal. to the finest German silver, be-
ing very malleable, homogeneous, strong and ductile, and
stands hammering, chasing, punching, etc., perfectly.
The proportion of aluminium in these bronzes last described
is so small that it appears probable that its chief function must
be as a deoxidizing agent, since a very small amount of oxygen
dissolved in the bath would quickly combine with all the alu-
minium added. In any event, very little can be left over, ap-
parently too little to be able to account for all the improvement
made in the alloy.
5l6 ALUMINIUM.
Cowles Bros, have manufactured some of these bronzes, and
have appropriated the name "Aluminium Silver" to the alloy-
made by adding aluminium to German silver, or to their alloy
of aluminium, nickel, and copper called "Hercules Metal."
Two of their alloys were made of —
I. II.
5 per cent, aluminium bronze i 2
Nickel 2 I
containing respectively —
I. II.
Copper 31.67 63.33
Nickel 66.67 33-33
Aluminium 1.67 3.33
These alloys, on being tested, gave tensile strengths of 79,163
and 1 18,000 lbs. per square inch respectively, the first showing
33 per cent, elongation. They claim that an alloy of the pro-
portions of II. will show an average strength of over 90,000
lbs. per square inch, but with very little elongation, and will
take an edge in a manner that makes it quite suitable for table-
knives.
G. F. Andrews* states that the following alloys are all very
hard, fine grained, and show great strength.
Aluminium. Nickel. Copper.
(I) 61^ 2ii^ 721^
(2) 10 24 66
(3) 12 33 5S
(2) has the color of ten carat gold and takes a fine polish 1(3)
has a beautiful golden-brown color ; ( i ) is similar, but richer
and deeper. These alloys may become very useful for decora-
tive purposes.
Aluminium and Phosphorus.
Wohler found that finely-divided aluminium, heated in phos-
phorus vapors, burns and forms a dark-gray metallic mass,
* Jour. Am. Chemical Society, July, 1 894, p. 486.
ALLOYS OF ALUMINIUM. 517
smelling strongly of phosphoretted hydrogen ; it also evolves
this gas copiously when placed in water.
Shaw's phosphor-aluminium bronze is described in Chap. XV.
Aluminium and Platinum.
Aluminium alloys readily with platinum, forming alloys more
or less fusible according to the proportion of aluminium.
Tissier Bros, state that an alloy with 5 per cent, of platinum
approaches in color gold containing 5 per cent, of silver, but is
not malleable enough to be worked. Debray says that a small
quantity of platinum (no definite amount named) can be toler-
ated in aluminium without the malleability being destroyed.
Aluminium and Silicon.
Deville : " Any siliceous material whatever, put in contact
with aluminium at a high temperature, is always decomposed ;
and if the metal is in excess there is formed an alloy or a com-
bination of silicon and aluminium in which the two bodies may
be united in almost any proportions. Glass, clay, and the earth
of crucibles act in this way. However, aluminium may be
melted in glassware or earthen crucibles without the least con-
tamination of the metal if there is no contact between the metal
and the material ; the aluminium will not wet the crucible if put
into it alone. But, the moment that any flux whatever facili-
tates immediate contact (even sodium chloride does this) the
reaction begins to take place, and the metal obtained is always
more or less siliceous. It is for this reason that I have pre-
scribed in melting aluminium not to add any kind of flux, even
when the flux would not be attacked by the metal. Among
the fusible materials which facilitate the melting of aluminium,
it is necessary to remark of the fluorides that they attack the
sihceous materials of the crucible, dissolving them with great
energy, and then the siliceous materials thus brought into solu-
tion are decomposed by the aluminium with quite remarkable
facility. Aluminium charged with silicon presents quite dif-
ferent qualities according to the proportion of the alloy. When
5 I 8 ALUMINIUM.
the aluminium is in large excess, there is obtained what I have
called the 'cast' state of aluminium, by means of which I dis-
covered crystallized silicon in 1854. This 'cast' aluminium,
gray and brittle, contains according to my analysis 10.3 per
cent, of silicon and traces of iron. When siliceous aluminium
is attacked by hydrochloric acid, the hydrogen which it disen-
gages has an infected odor, which I formerly attributed to the
presence of a hydrocarbon, but which we now know is due to
hydrogen silicide, SiH4, thanks to the experiments of MM.
Wohler and Buff. It is by the production of this gas that may
be explained the iron smell which is given out by aluminium
more or less contaminated with silicon. But aluminium may
absorb much larger proportions of silicon, for, on treating fluo-
silicate of potash with aluminium, M. Wohler obtained a mate-
rial still metallic containing about 70 per cent, of silicon, some-
times occurring as easily separable crystals. Since I had the
occasion in a work which I published on silicon to examine a
large number of these combinations, I found that they were
much more alterable than pure aluminium or silicon, without
doubt because of the affinity which exists between silica and
alumina. I have, therefore, dwelt on and tried to explain the
importance of this point in obtaining perfectly pure alu-
minium."
A small amount of silicon does not appear to be very inju-
rious to the malleability of aluminium, which bears it much as
iron and copper do, but over i or 2 per cent, commences to
change its color, make it harder and, especially, crystalline, so
that its malleability is rapidly impaired. The silicon, however,
may be present up to even 5 per cent, without preventing the
use of the metal for castings and articles not to be worked.
Minet has proven that aluminium may contain even 8 per
cent, of silicon and yet be quite strong, if the amount of iron
present is small ; but if the iron increases over i per cent., the
metal becomes worthless.
The double role of silicon in aluminium, as combined and
graphitoidal, was first pointed out by Rammelsberg (see p. 56),
ALLOYS OF ALUMINIUM. SI9
and is now being noted in the analyses of the metal. It does
not appear that chilling the metal has any influence in chang-
ing one kind into the other, and no fixed rule has yet been ob-
served as to the relative amounts of each kind existing in the
metal.
Aluminium and Selenium.
Wohler* stated that if selenium and aluminium are mixed in-
timately and heated together, they unite with a flame, leaving
a black, pulverulent, metallic powder, which smells strongly of
silicuretted hydrogen and evolves that gas violently when
dropped into water. The Hquor is colored red from precipi-
tated selenium.
Aluminium and Silver.
These alloys are easily made by direct fusion together of the
two metals. All the alloys containing up to 50 per cent, of
silver are more fusible than pure aluminium. In general, the
introduction of a few per cent, of silver into aluminium benefits
it considerably, increasing its hardness, capability of polish,
making it whiter, denser and stronger. It has already been re-
marked that aluminium will absorb almost 5 per cent, of silver
without increasing in volume. A great advantage gained by
this small amount of silver is also the increased facility of cast-
ing, the metal filling the moulds better and shrinking less ; this
alloy also rolls, draws, and works under the hammer like pure
aluminium, requiring, however, more power to work it. Deville
states that the alloy containing 3 per cent, of silver is unat-
tacked by sulphuretted hydrogen, but Mierzinski states that
every alloy of aluminium and silver is blackened more quickly
than pure silver. I think the latter remark untenable, since the
alloys with 3 to 5 per cent, of silver are noted for keeping their
color like pure aluminium in places where silver would be im-
mediately tarnished. With over 10 per cent, of silver, Mier-
zinski's remark may be true. M. Christophle made statuettes of
* Pogg- Ann., 1827, ii, 160.
520 ALUMINIUM.
the alloy with 3 per cent, of silver, which kept their beautiful
white color permanently,
With 5 per cent, of silver, aluminium becomes elastic and as
hard as coin silver with 10 per cent, of copper, but is still as
malleable as pure aluminium. It has a specific gravity of 2.8,
casts better than aluminium, shrinks less, and can be rolled or
drawn perfectly, but requires more power than pure aluminium.
It has been used for dessert-spoons, knife-blades, and even for
watch-springs. This is the alloy which has often been pro-
posed as a substitute for coin silver, since it contains no such
poisonous metal as copper, and the color is not appreciably
dififerent from that of pure silver. The beams of fine balances
when made of aluminium contain from 3 to 5 per cent, of silver.
The alloy with 3 per cent, of silver and 2 per cent, of copper,
strongly compressed cold, is also recommended.
The alloy containing 10 per cent, of silver is much harder
than the foregoing. It casts well, and can be rolled at a par-
ticular heat, but it does not work well under the hammer. Dr.
Carroll, manufacturer of dental plates, uses an alloy for casting
these articles* composed of —
Aluminium 90 to 93 parts.
Silver 5 to 9 "
Copper I "
This alloy, when cast under slight pressure, gives perfett
castings, is very white and easy to work. The addition of cop-
per is said to decrease to a minimum the shrinkage of the alloy,
also giving it a closer grain.
The alloys containing from 10 to 50 per cent, of silver are
all brittle and cannot be worked under the hammer. Debray
states that the 50 per cent, alloy is as hard as bronze. "Tiers
Argent" is an alloy of two-thirds aluminium and one-third sil-
ver. It is chiefly made in Paris ; its advantages over silver are
that it is cheaper, harder, and can be stamped and engraved
with greater ease than the alloys of silver and copper. Some
* U. S. Patent 373,221, Nov. 15, 1887.
ALLOYS OF ALUMINIUM. $21
difficulty was met, at first, in getting the alloy homogeneous ; but
this has been overcome, and spoons, forks, salvers and articles
generally made of silver are now made of this metal with an ap-
pearance equal to that of any other silver alloy. Tissier Bros,
stated that the alloy with 33 per cent, of silver (the same as
"Tiers Argent") is fusible enough to be used as a solder for
aluminium, but they found difficulty in running it out, and also
found that it made a brittle joint.
Hirzel* made alloys of aluminium and silver in atomic pro-
portions, containing from 6 to 20 per cent, of aluminium. He
found the alloy AlAg, containing 20 per cent., to be silver-
white, very porous, tarnishing in the air, with a specific gravity
of 6.73 ; the alloy AlAg^, containing 11. 11 per cent., to be also
silver-white, less porous, also tarnishing in the air, specific
gravity 8.744; and the alloy AlAg^, containing 5.9 per cent., to
be pure silver-white, very malleable and forgeable, tarnishing
in the air and with a specific gravity of 9.376.
Aluminium and Sodium.
Deville states that aluminium unites easily with small propor-
tions of sodium ; with i to 2 per cent, it decomposes water in
the cold. It follows from this that the properties of the metal
made carelessly by using sodium are completely altered. The
last traces of sodium can be removed only with great trouble,
especially when the aluminium has been produced in presence
of fluoride, because of the marked affinity of aluminium for
fluorine at the temperature at which aluminium fluoride, AIF3,
commences to volatilize.
Aluminium and Tellurium.
Wohler states that when heated together in powder, these
elements combine very violently, leaving a black, brittle, metal-
he mass, smelling strongly of tellurretted hydrogen and evolv-
ing that gas actively when put into water. The water becomes
first red, then brown, and finally opaque, from precipitated tel-
*Bayerisches Kunst und Gewerb-Blatt, 1858, p. 45'-
522 ALUMINIUM.
lurium. Put on paper, a piece of this alloy forms a brown, me-
tallic ring around it. Wohler noted that it decomposed water
even more energetically than aluminium sulphide.
Aluminium and Tin.
These two metals unite readily, small amounts of either
metal changing the properties of the other quite materially.
A small amount of tin renders aluminium brittle. Tissier
Bros, made an alloy with 3 per cent, of tin, melting the metals
under sodium chloride, then remelting once without any flux.
This alloy was a little more fusible than aluminium, but very
brittle ; the grain was very fine and crossed, but the bar broke
at the first blow. Deville stated that these alloys with a small
proportion of tin may be used as solders for aluminium, but they
answer only imperfectly.
M. Bourbouze* has recommended the use of an aluminium-
tin alloy for the interior parts, especially, of optical instruments,
in place of brass. The alloy formed of 100 aluminium to 10 of
tin, or 9 per cent, of tin, is recommended as being the best for
this purpose. It is white and has a specific gravity of 2.85,
only slightly above that of aluminium itself. It may therefore
be used in place of aluminium where great lightness is desired,
and it is further superior to aluminium itself in resisting altera-
tion better, being more easy to work, and finally it can be sojd-
ered without any special apparatus, as easily as brass, particu-
larily if the solder recommended by M. Bourbouze (p. 463) is
used. If the alloy does work as well as represented by Bourbouze,
there must be a very sudden change in the properties of alu-
minium alloys between the 3 per cent, tin alloy described by
Tissier Bros, and this 9 per cent, alloy; but from analogy
with other aluminium alloys we admit that this is not im-
possible. Having so many advantages over aluminium it
should replace it for many purposes, especially in instruments
of a portable character ; it would, besides, be somewhat cheaper
*Comptes Rendus, cii., p. 131 7.
ALLOYS OF ALUMINIUM. 523
than pure aluminium. An analysis of some of this metal ex-
hibited at the Paris Exposition of 1889 gave
Aluminium 85.74 per cent.
Tin 12.94 "
Silicon 1.22 "
Iron .
none.
A test by Minet of a similar alloy, containing tin 10 per cent,
aluminium 88, silicon i;30, iron 0.65, gave a tensile strength in
casting of 9.8 kilos per square m. m. (14000 pounds per sq.
in.) with an elongation of only 4. 11 per cent. It thus appears
that this alloy is in reality not quite so strong as aluminium
itself.
At the other end of the scale we have alloys containing only
a few per cent, of aluminium. Aluminium gives to tin greater
hardness and tenacity if it is not present in too large an
amount. The alloy with 3 per cent, of aluminium is harder
than tin and less acted on by acids ; 5 per cent, of aluminium
gives a much stronger and more elastic metal. The alloy with
7 per cent, of aluminium is especially recommended as being
easy to work, being malleable at a red heat, and capable of a
good polish, but possessing the drawback that it cannot be
melted without a part of the tin separating from the aluminium.
Tissier Bros, state that tin will not combine with more than 7
per cent, of aluminium, for they state that the alloy with 10
per cent, is not homogeneous, and on cooling in a mould ar-
ranges itself in two layers, an upper brittle one, a little more
fusible than aluminium, and a lower one containing nearly all
the tin, but rendered harder and less fusible than pure tin by a
small quantity of aluminium. I have not been able to notice
this liquation. Mr. Joseph Richards prepared an alloy with 10
per cent, of aluminium, which was whiter and much stronger
than tin and kept its color perfectly in the air. It had a specific
gravity of 6.45 (calculated value 6.28) and melted only imper-
fectly at a temperature slightly above that of tin. It was quite
malleable, but became hard by rolling. On heating a piece of
S24 ALUMINIUM.
this, in the form of sheet, at a gradually increasing temperature,
small globules sprouted out in all directions, but they were
identical in composition with the bulk of the alloy, so that no
separation had taken place. The surface of the sheet appeared
harder than the interior, and did not melt so easily, but this
property seemed to result from other causes than difference in
composition. After standing several months a peculiar inter-
nal change took place in this metal by which it lost all its mal-
leability and became as rotten as baked clay, and annealing
could not restore its strength.
The same disintegration has been noticed with even smaller
proportions of aluminium. A metal company in Philadelphia,
which makes tin foil, tried the experiment of adding less than
I per cent, of aluminium to their metal. It rolled beautifully
and had a fine color, but in a few hours it became brittle, and
in a few days it had all fallen to powder.
Heycock and Neville have noticed that very small amounts
of aluminium lower the melting point of tin, a minimum freez-
ing point of 3 degrees lower than tin itself being obtained with
0,48 per cent, of aluminium. Very careful experiments showed
this lowering to be, within the limit of 0.25 per cent, alumin-
ium, at the rate of 1.3° fall per i atom weight of aluminium
dissolved in 100 atom weights of tin.
The alloy with 19 per cent, of aluminium is said to be mal-
leable and workable at a red heat, though not so much so* as
the 7 per cent, alloy. The alloys with over 30 per cent, of alu-
minium are described as silver-white, porous and brittle.
Minet found the alloy of 50 tin, 48.9 aluminium, 0.72 silicon
and 0.36 per cent, iron to be malleable, but when forged it had
a tensile strength of only 10 kilos per sq. m. m. (15,000 lbs.
per sq. in.) with practically no elongation.
The melting' points of a number of these alloys have been
determined by Minet as follows, making the alloys with com-
mercial aluminium containing 1.50 per cent, silicon and 0.76
per cent, iron, whose melting point was 619° C. : —
ALLOYS OF ALUMINIUM. 525
Comme'cial aluminium. Tin. Fusing point,
100 o 619^ C.
92 8 595°
80 20 .....575°
7° 30 535°
60 40 575°
5° 50 570°
20 80 530°
10 90 490°
o 100 233°
Two points are worthy of particular attention in this table.
First, that 10 per cent, of aluminium serves to raise the melting
point over 250°, or 60 per cent, of the total difference between
the melting points of the two metals. Second, the sudden drop
at 30 per cent, tin, which looks almost as if a mis-print had
been made. The alloy Ali„Sn would correspond to 30.4 per
cent of tin. By a peculiar co- incidence, there will be noted in
the melting points of aluminium-copper alloys a similar sudden
fall at 20 per cent, of copper, and oddly enough, the alloy
AlioCu calls for 19 per cent.
Aluminium and Titanium.
Wohler* obtained an alloy by melting together —
Titanic oxide 2 parts.
Cryolite 6 "
Potassium and sodium chlorides 6 "
Aluminium I "
The excess of aluminium being dissolved out of the mass by
caustic soda, bright, steel-colored crystals remained, containing
aluminium, titanium, and a little iron and silicon from the
aluminium used. The specific gravity was 3.3 ; the alloy was
infusible before the blowpipe, but on ignition in chlorine gas
burnt, forming chlorides of all the metals present. Its composi-
tion seemed to vary, for another experiment at a lower tempera-
ture gave an alloy richer in silicon, with a specific gravity of
2.7. On heating these alloys in the air they first become
yellow, then steel-blue, and after that oxidize no further.
*Ann. der Chem. und Pharm., 113, 248.
526 ALUMINIUM.
Michel, proceeding in a similar way, obtained an alloy whose
analysis denoted the formula AlsTi, containing about 62 per
cent, of aluminium.
L. Levy* describes an alloy which he obtained by similar
processes, as being in crystalline plates, insoluble in water,
alcohol, or ether, steel-gray in color, brittle, and conducting
heat and electricity. Specific gravity 3.11 : composition on
analysis —
Aluminium 70.92
Titanium 26.80
Silicon 2.1 7
In 1 89 1, the Pittsburgh Reduction Company began to manu-
facture alloys of aluminium with 0.5 to 2 per cent, of titanium
by a process analagous to Wohler's. Cryolite is melted in a
carbon-lined crucible, and titanic oxide dissolved in it. After
thorough solution, aluminium is introduced, solid or liquid, and
the heat continued. The titanic oxide which has been added
will be completely reduced to titanium, which alloys with the
aluminium, and the per cent, of titanium in the alloy is regu-
lated by the weight of aluminium added. These alloys are
harder than aluminium, and when rolled have a degree of
elasticity comparable to spring brass, with a tensile strength of
30,000 to 40,000 pounds per sq. inch. If chromic oxide is ad-
ded to the bath as well, a triple alloy of aluminium, titanium
and chromium is obtained which is very hard and rigid. The
titanium alloys alone will bear a cutting edge about as well as
soft steel, and have been already used for potato and fruit knives.
Lejeal made an alloy with 7 per cent, of titanium, and calls
attention to its peculiar fracture, which is traversed by sharp
lines like the top of a butcher's block.
The following mechanical tests were made in Le Verrier's
laboratory :
* Comptes Rendus, 106, 66, (i
ALLOYS OF ALUMINIUM. 527
Titanium. Tensile Strength. Elongation
Per cent. Kilos per sq.m.m. Pounds per sq. in. Per cent.
2.9Z (rolled poorly) 19 27,000 2.5
2.20 (rolled well) 24 34,000 5.0
1.70 (rolled well) 20 28,000 1.5
" (annealed) 15 21,000 16.5
These results agree with the experience of the Pittsburgh
Company, who have found 2 per cent, to be about the strong-
est alloy. While these alloys are very strong, yet they are not
of as fine color as pure aluminium, being somewhat leady in
appearance, and they do not solder so easily. Still, for pur-
poses where great strength and elasticity combined with light-
ness are the prime requisite, and looks are a secondary consid-
eration, the 2 per cent, alloy can be highly recommended.
Aluminium and Tungsten.
Michel fused together —
Tungstic acid 3 parts.
Cryolite 6 "
Potassium and sodium chlorides 6 "
Aluminium 3 "
at a strong red heat. The fusion was afterwards treated with
hydrochloric acid, leaving an iron-gray, crystalline, brittle pow-
der, single crystals being several millimetres long. Hot caustic
soda extracted from them all their aluminium, leaving pure
tungsten. Their specific gravity was 5.58, and the composi-
tion corresponded to the formula Al^W, containing 37 per cent,
of aluminium.
Mannesmann recommends the addition of small quantities of
tungsten for improving the resistance of aluminium to corrosion.
He also claims greatly increased strength.
Tests made in Le Verrier's laboratory show properties similar
to the titanium alloys. The following are the properties of the
alloy with 7.5 per cent, of tungsten :
Tensile Strength. Elongation.
Kilos per sq, m.m. Pounds per sq. in. per cent.
Cast 15.5 22,000 1.5
Rolled hard 25.0 3S>ooo 4.0
Annealed 18.0 25,000 lo.o
" 15.9 22,000 14.0
528 aluminium.
Aluminium and Zinc.
Aluminium unites readily with zinc, the alloys being in gen-
eral harder and more fusible than aluminium. Some of the
first attempts to solder aluminium were with these alloys, con-
taining 6, 8, 12, 15, and 20 per cent, of aluminium. They an-
swered better than any other solders which had been tried, but
unfortunately, when melted they are thick and run with difiS-
culty, so much so that it is necessary to spread them over the
joint as a plumber does when he wipes the joints of lead pipes.
Joints thus made stand hammer blows or rough usage very
poorly.
The alloy containing 10 per cent, of aluminium is brittle, has
the appearance of zinc, is more fusible than aluminium and less
so than zinc. The alloy with 25 per cent, of aluminium has a
fine, even grain, and is of about the same fusibility as the pre-
ceding. The alloy AlZn, containing 29.5 per cent, of alumin-
ium, forms a silver-white, very brittle, crystalline alloy, with a
specific gravity of 4.53. It was noticed that in the preparation,
when the two metals were fused together in this proportion
. under a layer of sodium and potassium chlorides, they united
with incandescence. The 50 per cent, alloy is white, crystalline,
brittle, and does not appear to be homogeneous, for the Tis-
sier's report that when heated on an aluminium plate it sepa-
rated into a fusible portion which ran off, and a less fusible
part which did not melt until the plate did.
When zinc is in small proportion in aluminium it makes it
brittle, unless below a very few per cent, in quantity. The
alloy containing 3 per cent, of zinc is described by Debray as
harder than .aluminium, very brilliant, but still quite malleable.
Some of the aluminium first made by Deville contained zinc,
the presence of which he accounted for as follows: "The re-
torts used for making the aluminium were made at the Vielle
Montagne Zinc Works, and having in their mixture some
ground-up old zinc retorts, the new retorts contained zinc,
which passed into the aluminium and altered its properties in a
very evident manner. Some analyses of this metal having been
ALLOYS OF ALUMINIUM. 529
made in England, some asserted that French aluminium was
only an alloy to which zinc gave a fusibility which might be
wanting in pure aluminium.
The addition of both zinc and copper to aluminium makes a
very stiff metal in castings. Alloys with five per cent, copper
and I S per cent, of zinc, also 3 per cent, copper and as high as
27 per cent, of zinc have been used very successfully in cast-
ings where great rigidity was desired. If such castings are
made under pressure they are still stronger.
Aluminium has found considerable use in the zinc industry.
Mr. Joseph Richards, of the Delaware Metal Refinery, Philadel-
phia, has patented * the addition of a very small amount of alu-
minium to the galvanizing bath. An alloy is prepared contain-
ing 2 per cent, of aluminium, and it is recommended to add i
pound of this alloy to each ton of zinc in the bath. ,The efifect
is to make the zinc more fluid, a given weight coating 20 per
cent, more surface, and the sheets produced being brighter and
keeping their color better. The bath also oxidizes less, and so
produces less skimmings, although, as the metal is rendered
more fluid, the per centage of " dross bottoms" {i. e. impurities
settling out of the zinc) is increased. As the amount of alu-
minium added is only o.ooi per cent., the cause of its marked
effects seems difficult to explain. It has seemed to the writer
that it acts chemically on dissolved oxygen or dissolved oxide
of zinc in the bath, which substances have a strong tendency to
render the metal thick or mushy. By completely eliminating
the last trace of these ingredients, the aluminium gives the bath
its maximum fluidity. The beneficial effects, in fact, are so well
established that almost every galvanizer in the United States is
already using Mr. Richards' process.
Similar advantages are gained by using a small percentage
of aluminium in the zinc used in desilverizing (Parke's process).
Here zinc is stirred into silver-lead, and kept at a low red-heat
for several hours, and the addition to it of aluminium gives it
much greater resistance to oxidation. With i per cent of alu-
* U. S. Patent, March, 1891.
34
530 ALUMINIUM.
minium the zinc will remain clear and white, even at a
red heat. The improvement can be noted with even o.i per
cent. Instead of repeatedly adding zinc to the lead in several
kettles, the whole of the silver may be removed from the lead
in one operation. A German patent of Rossler * recommends
using as high as 0.5 per cent, of aluminium. The scums are
removed on cooling the bath, and are almost entirely free from
oxide, thus allowing them to be liquated easily with very lit-
tle loss, and giving a rich zinc -silver alloy almost entirely free
from lead or oxides. The small amount of aluminium used is
almost entirely oxidized out during the process; but if the
scums are burnt to zinc oxide, what aluminium is left passes as
alumina into the zinc oxide.
A luminium-Zinc- Copper A Hoys.
These alloys are generally known as " aluminium brasses,"
and are about as much superior to ordinary brass as aluminium
bronze is to ordinary bronze. They are made in two general
ways ; either by introducing metallic aluminium into melted
brass, or by introducing zinc into melted aluminium bronze.
The latter method is pursued by the Cowles Smelting Com-
pany, because they produce the bronze directly, while the
makers of pure aluminium claim that the first method is su-
perior, because by adding aluminium to melted brass the dis-
solved cuprous oxide and zinc oxide are removed, producing a
dense metal, casting without pores, while the aluminium already
combined with copper does not have this effect. It appears,
however, that the Cowles brasses are equal in strength, elonga-
tion, and casting qualities to those made with pure aluminium.
Repeated remeltings of aluminium brass are not advisable,
since, like all brasses, it changes in composition on melting,
though not to so large a degree. After mixing, it need be re-
melted only once in a clean crucible. Aluminium brasses flow
well, give sharp, sound castings, are more ductile, malleable,
and have greatly increased strength and power to resist cor-
* No. 64,416, 1892.
ALLOYS OF ALUMINIUM. 53 I
rosion. The working qualities are said to be governed largely
by the percentage of zinc present, an increase of which makes
the brass harder, but does not injure its malleability.
Numerous tests have been made of the strength and elonga-
tion under stress, of aluminium brasses. Even i per cent, of
aluminium is found of benefit, while the strength increases with
the amount of aluminium.
As early as 1863, Julius Baur, of New York, obtained a
patent* for alloys containing —
Copper 14-16 parts.
Zinc 10 "
Aluminium 0.1-3 "
which he stated were of great hardness, toughness and dura-
bility. This alloy differs from the aluminium brasses now made
only in containing about half as much again of zinc. The next
year, M. G. Farmer, of Salem, Mass., patentedf an alloy con-
taining—
Copper 65-80 parts.
White metals 3S-io "
Aluminium 0.3-10 "
Cowles Bros, report the following series of tests made, in
1886, at their works in Lockport, their alloys all being made by
adding zinc to aluminium bronze :
Composition. Tensile strength per Elongation,
Aluminium. Oopper. Zinc. sq. inch (castings 1. percent.
5.8 67.4 26.8 95.712 I.O
3-3 63.3 33.3 85,867 7.6
3.0 67.0 30.0 67,341 12.5
i.S 77-5 21.0 32,356 41-7
1.5 71.0 27.5 41.952 27.0
1.25 70.0 28.0 35.059 25.0
2.5 70.0 27.5 40,982 28.0
1.0 57.0 42.0 68,218 2.0
1.15 55.8 43.0 69,520 4.0
*U. S. Patent, 40388, Oct. 1863.
tU. S. Patent, 44086, Aug., 1864.
532 • ALUMINIUM.
When it is remembered that ordinary brass rarely has a ten-
sile strength over 30,000 lbs., with elongation about 10 per
cent., the benefit of the aluminium can be easily realized. Gov-
ernment tests of this company's brasses, to determine their
suitability for steamship propellers, were made on the alloy
composed of i part 10 per cent, bronze, i part copper and i
part zinc, containing therefore —
Aluminium 3.3 per cent.
Copper 63.3 "
Zinc 33.3 "
The test pieces were 22 inches long, i % inches diameter, and
10 inches between elongation marks. The results showed a
tensile strength of 70,000 to 82,500 lbs., elastic limit 55,000 to
65,000 lbs., and elongation 1.6 to 2.5 per cent.; having, there-
fore, a tensile strength three times and elastic limit four times
as great as the best Government bronzes.
The Aluminium und Magnesium Fabrik, of Bremen, state
the strength of aluminium brass according to their tests to be —
2 aluminium, 23 zinc, 75 copper 41,000 lbs.
2 " 30 " 68 " 49.530 "
2%. " 30 " 671^ " 65,400 "
Prof. Tetmayer, of Zurich, has tested the strength of alumin-
ium brasses with the following results : —
Strength. ^,
, A ^ Elongation,
Content of aluminium. Kilos per sq. mm. Lbs. per sq. in. per cent.
4 per cent. 69 98,100 6J^
3 " 60 85,300 7>4
2>^ " 52 73.900 20
2 " 48 68,250 30
13^ " 45 64,000 39
I " 40 56,900 50
The amount of zinc in these brasses is not stated, but was
probably 25 to 30 per cent.
In general, then, we may conclude that even a fraction of i
per cent, of aluminium added to brass will increase very re-
ALLOYS OF ALUMINIUM. 533
markably its strength and ductility, while about 5 per cent, will
make an alloy, having brought its tensile strength close up to
100,000 lbs. per square inch. This indicates that as far as
strength alone is concerned the cost of aluminium brass castings
is less than aluminium bronze castings of the same strength, for
they contain less aluminium and a quantity of the cheap metal
zinc. The principal disadvantage of the brass compared with
the bronze is, that it cannot be remelted without changing its
quality, by reason of its containing zinc.
A remarkable property of the aluminium brasses, however, is
their capability of forging at a red heat; even 0.5 per cent,
added to ordinary brass imparting to it this quality.
A very strong and, at the same time, cheap alloy is that
known as " Richards' Bronze," the invention of Mr. Joseph
Richards of Philadelphia. It contains copper 5 5 parts, zinc 42
or 43, iron i, aluminium i to 2. This alloy is of a golden-
yellow color, is exceedingly fine-grained, and has a tensile
strength in castings of 50,000 pounds per square inch with 15
per cent, elongation. Like all the strong bronzes, however, it
requires some experience in handling before the ordinary
metal-worker can turn out uniformly castings with these maxi-
mum properties. The worked metal averages 50 per cent,
stronger.
CHAPTER XV.
ALUMINIUM-COPPER ALLOYS.
These two metals unite readily in many proportions, the
union being attended with evolution of heat, which in some
cases is very large in amount. As has been noticed with re-
gard to the alloys of other metals with aluminium, so here we
note that the useful alloys of these two metals are in two
groups, 1st — those in which a small percentage of copper im-
parts certain advantageous properties to aluminium ; 2d — those
in which a limited quantity of aluminium enhances the useful
properties of copper. The latter is by far the class of most im-
portance industrially.
* General Properties.
The color of aluminium-copper alloys is white until the per-
centage of coppfer exceeds 80 per cent, or until its bulk be-
comes equal to that of the aluminium with which it is alloyed.
Above this amount of copper, the color becomes first slightly
violet and then yellowish, until with 90 per cent, the alloy is a
light golden yellow; at 92.5 per cent, the color is greenish-
gold; at 95 per cent, the full color of 18 carat gold alloyed
with silver; at 97.5 per cent, the color of 18 carat gold alloyed
with copper ; above that amount, the color of red brass.
Le Verrier has made a study of the melting points of the
aluminium-copper alloys by means of the Le Chatelier pyro-
meter, and has published the following results for alloys of
commercial aluminium :
(534)
ALUMINIUM-COPPER ALLOYS. 535
Composition.
Aluminium.
Silicon.
Iron.
Copper.
Melting Point (C°)
100.00
62s
97-75
1.50
0.75
0
619
90.00
1.40
0.70
8
587
89.00
1-35
0.68
10
578
83.00
1.28
0.64
IS
573
78.20
1.20
0.60
20
528
73-30
•-I3
0.56
25
553
65-5°
1. 00
0.50
33
527
58.70
0.90
0.45
40
535
48.90
0.7s
0.38
50
553
36.70
0.56
0.28
62.5
545
29.30
0-45
0.23
70
692
22.00
0-34
0.17
77-S
694
19.60
0.30
0.15
80
947
12.20
0.19
0.09
87-S
974
9.80
0.15
0.07
90
1029
7-3°
0.1 1
0.05
92-S
1000
4.90
0.08
0.04
95
100
1030
1054
If these melting points are carefully examined, several pecu-
liarities are noticed, indicating chemical alloying. The natural
compounds of aluminium and copper are those with the for-
mulae AlCuj and AljCuj, containing respectively 12.4 per cent
and 22 per cent, of aluminium. Both these alloys are well
marked. The first melts completely without liquation and
crystallizes in prisms, while all the alloys with a smaller pro-
portion of aluminium have a serrated fracture. The fall of the
melting point at 7.5 per cent, of aluminium indicates combina-
tion at this point, and its formula, AlCuj, may be understood as
A\Cu^ plus Cuj, indicating that it is a chemical combination of
the 12.4 per cent, alloy with a definite amount of copper. Its
behavior on cooling supports this view, by showing indications
of free copper in passing the melting point of copper. It is
also interesting to note, that if we consider the specific gravities
of the two metals, the alloy AlCuj consists of a combination of
one volume of aluminium to two volumes of copper, truly a
very simple relation.
The alloy Al^Cu., is also very sharply defined. It contains
536 ALUMINIUM.
22 per cent, of aluminium, but its melting point, 994°, is 250°
lower than that of the alloy with 20 per cent. That a differ-
ence of only 2 per cent, in composition should make this ex-
treme change in fusibility is very curious. This alloy, more-
over, consists by volume of equal parts of aluminium and
copper, and it is at this point that the yellow color of the lower
alloys fades out entirely, and the alloy is white.
Another sharp fall in the melting point at 37.5 per cent, of
aluminium indicates the alloy AljCuj, in which the proportions
of the two metals combined by volume is 2 aluminium to i of
copper. Its melting point is 545° C, or 80° below that of alu-
minium alone ; a fact which is very remarkable considering
that the alloy contains over half of its weight of copper.
From this point until the percentage of aluminium is over 80,
the melting point remains between 500° C. a;nd 550°, with pos-
sibly definite alloys at AljCu (68 per cent.) and AluCu (81 per
cent). What the true constitution of these alloys is must be
left to conjecture. They are probably definite compounds of
AI2CU3 with fixed quantities of aluminium ; or, as we might put
it, AI2CU3 dissolved in a certain excess of aluminium.
From 85 per cent, of aluminium, the melting point rises;
from 90 per cent, upwards at a nearly uniform rate of 4° for
each per cent, increase. We therefore note the singular fact,
that the addition of copper to aluminium, in amounts up to 10
per cent., lowers the melting point of the latter about 4° for
every per cent, of copper present.
The study of the specific gravities of these alloys would be
most interesting, but, unfortunately, the data are largely wanting.
Alloys of the First Class.
A small percentage of copper hardens aluminium, but does
not take away its malleability. I have observed that a very
small amount, less than o.i per cent., closes the grain of com-
mercial aluminium, making it look more compact, and for that
reason whiter, on a fractured surface. This small amount
makes the aluminium perceptibly harder. It has been ob-
ALUMINIUM-COPPER ALLOYS. 537
served that by adding a small amount of copper to aluminium
much better castings are obtained and with greater ease than
with pure aluminium. The reason is probably that the copper
is mostly absorbed into the aluminium, so that it shrinks less in
cooling and casts more solidly. Christofle, of Paris, exhibited
at the London Exhibition in 1862, statuettes of a beautful sil-
ver-white color made of aluminium with i per cent of copper.
Deville states that the addition of 2 or 3 per cent, of copper
was found useful in making large art-castings, and that the
alloy produced worked very well under the chisel and burin.
The metal reduced by Deville in copper boats (see p. 255)
contained from 5 to over 6 per cent, of copper, yet it could be
worked easily. This malleability is retained until the copper
exceeds 10 per cent., above which quantity brittleness sets in.
Cowles Bros, report the alloy with 16.8 per cent, of copper as
having a specific gravity of 3.23, tensile strength 29,370 lbs.
per square inch, but elongation almost nothing, the alloy being
too brittle for any practical use. Alloys containing from 30 to
40 per cent, of copper are very brittle, and hard as glass and
beautifully crystalline.
The alloys with small percentages of copper have recently
been in great favor with constructors of aluminium apparatus,
boats, etc. The works at Froges, France, makes regularly a 6
per cent, alloy which rolls well, and has the following mechan-
ical properties :
Tensile Strength.. Elongation.
Treatment. Kilos per sq. m. m. Pounds per sq. in. Per cent.
Rolled hard 25 35,000 3.5
Annealed 18 25,000 15.5
Captain Julien made experiments with these alloys at the
Aerostatic Park at Meudon, and gives the following properties
of sheet i milHmetre thick cut in strips 5 millimetres wide :
Observed.
Calculated.
Tensile Strength.
Per cent, of Copper.
Specific gravity.
Specific gravity.
Kilos per sq. m.
m.
Pounds per sq. in
0
2.67
2.67
18.7
26,500
2
2.71
2.71
30-7
43.500
4
2.77
2.7s
3I-I
44,000
6
2.82
2.79
38.6
55,000
8
2.84
2.83
39-S
56,000
538 ALUMINIUM.
These light alloys do not resist corrosion as well as pure alu-
minium, but they cast well and are very suitable for many
purposes where lightness and strength together are wished.
The alloy with 2 to 3 per cent, of German-silver, first de-
scribed by the writer, may be also commended as being of a
fine white color, strong, and quite elastic. When rolled hard,
its tensile strength exceeds 40,000 pounds, -with an elongation
of 3 to 5 per cent., while in casting its strength is 22,000
pounds, or 50 per cent, stronger than aluminium. The fine
color and elasticity of this alloy commend it for many purposes
where pure aluminium is too soft and non-elastic.
Alloys of the Second Class.
Aluminium is more efficient than any other metal in improv-
ing the qualities of copper. Under this second head we shall
consider these alloys made by adding to copper any quantity of
aluminium up to the limit within which the alloys are of prac-
tical value. This limit has been definitely established at about
1 1 per cent. ; and the alloys here included are generally known
as " the aluminium bronzes," being particularized as i per cent,
bronze, 5 per cent, bronze, etc. ; but on account of its general
superiority over all the rest, the alloy with about 10 per cent,
of aluminium has received the title. of "aluminium bronze" —
without any qualifications. This distinction has come into gen-
eral use, and it will be well to keep it in mind in going over the
succeeding pages, for, whenever the expression " the aluminium
bronze'' or " aluminium-bronze'' occurs without the percentage
of aluminium being specified, the 10 per cent, alloy is signified.
The late Dr. Percy seems to have been the first to call atten-
tion to these beautiful alloys, but I am unable to find any ac-
count given by him beyond the statement that " a small pro-
portion of aluminium increases the hardness of copper, does
not injure its malleability, makes it susceptible of a beautiful
polish, and varies its color from red-gold to pale-yellow." This
statement must have been made prior to 1856. In that year,
Tissier Bros, brought aluminium bronze to the notice of the
ALUMINIUM-COPPER ALLOYS. 539
French Academy,* and a week later a paper by Debray.f hur-
riedly put together, made known the results obtained up to
that time by Messrs. Rousseau, Morin and himself at La
Glaciere.
Aluminium bronze went through the same experience that
aluminium itself and all its other alloys underwent during the
first decade after its discovery. It was unduly praised, too
much claimed for it, and so, while its wonderful properties did
sustain for a season all the exaggerations heaped upon it, yet
some unprejudiced observers soon made known the true state
of the case, and determined its proper place among the alloys ;
but, as even the high place finally accorded it was far below the
first expectations, we have seen the alloy become the subject
of unmerited fault-finding. If some people expect too much of
the alloy, and are therefore disappointed, let them blame them-
selves, or, perhaps, those who led them to expect so much,
and not the metal.
The history of the application of aluminium bronze is
summed up in the oft-repeated expression " it would come into
extensive use in the arts if its price would permit." Since, until
recently, it was made by melting directly together the copper
and aluminium, its price was naturally dependent upon that of
the latter metal, and by reference to the price of that metal in
dififerent years, it is an easy matter to figure out what one-tenth
of a kilo or pound of aluminium would cost to make a kilo or
pound of bronze. In 1864, Morin, of Paris, quoted the alumin-
ium bronzes at the following prices : —
10 per cent, aluminium 15 francs per kilo (I1.36 per lb.).
7>^ " " 12}4 " " («I.I4 " ).
5 " " 10 " " (;?o.9i " ).
During the years from i860 to 1883 the price of aluminium
remained almost constant, its use was not extended, and its
*Comptes Rendus, 43, 885 (Nov. 3, 1856).
tComptes Rendus, 43, 92s (Nov. 10, 1856).
540 ALUMINIUM.
bronze shared the same apathy. In 1 879, the Societe Anonyme
de TAluminium quoted —
10 per cent, aluminium bronze 18 francs per kilo (^(1.64 per lb.)
which does not show much improvement on the price of fifteen
years before. And so the bronze was kept out of almost
every possible industrial application until 1885, when the ap-
plication by Cowles Bros, of the electric furnace to the reduc-
tion of alumina in presence of copper brought the question of
aluminium bronze nearer to a practical solution than it had
ever been before. They sold the alloy at the start on the basis
of $3.50 per pound for the contained aluminium, which brought
the price down to —
10 per cent, aluminium bronze ^60.50 per lb.
For several years, the Cowles Company and the owners of
the Heroult process sold large amounts of aluminium bronze
on the basis of $2.50 per pound for the contained aluminium,
and in 1890 on the basis of $1.50 per pound, which made the
price of 10 per cent, bronze $0.30. However, when the price
of commercial aluminium dropped below $1.00 per pound, and
especially since it has reached $0.50, the bronze can be made
from the pure metals, in any grade desired, so cheaply and ac-
curately, that the sale for ready-made bronzes has well-nigh
vanished. Users of the bronzes prefer to do their own mixing,
and make the alloys according to their own formulae. With
copper worth $0.10 per pound, and aluminium $0.50, the
metals in 10 per cent, bronze cost only $0.14; and if the cost
of making is added, the total cost in ingots is not over $0.16
per pound. At such prices, there is no margin of profit left to
the makers of bronzes by the alloy processes. This reversal
of industrial conditions since 1890 has been a prominent fea-
ture of the aluminium industry.
Constitution of the bronzes. — The question whether the alu-
minium bronzes are chemical combinations of the two metals
composing them has long been argued pro and con. It is
ALUMINIUM-COPPER ALLOYS. 541
acknowledged that the bronzes containing about 21^, 5, "jY^
and a little less than 10 per cent, aluminium behave most like
true alloys, or chemical combinations in which the identity of
the constituents is sunk completely in that of the compound.
There is a coincidence to notice here, which would be remark-
able if it had no significance. The alloys represented by the
following formulas would contain respectively —
Cu^Al g.6i per cent, aluminium.
CugAl 5.05 "
CuieAl ••2.59
Cu,Al
7-i
With regard to these bronzes, Morin* advances the following
arguments to prove that they are true chemical combinations
according to the formulas given : —
1. The alloy made by melting 10 parts of aluminium with
90 parts of copper is a very brittle mixture, which only takes
on its best properties after two or three repeated fusions, during
which the excess of aluminium above that called for by the
formula is oxidized and separated out. When this point has
been reached, further meltings do not alter the properties any
more.
2. The addition of 5, 75^ and 10 per cent, of aluminium
gives perfectly homogeneous alloys, but if 6, 7 or 8 per cent, is
added, only metallic mixtures result, in which can be distin-
guished uncombined aluminium. A point worthy of remark
is that the color of the 5 and 10 per cent, bronzes is similar to
gold, the latter giving a brighter shade; but the 7^ per cent,
bronze is of a greenish cast, and has an entirely different ap-
pearance from the other two.
3. When 10 per cent, of aluminium is added to molten cop-
per, the large amount of heat absorbed by the aluminium cools
the copper so much that almost all of it becomes solid. How-
ever, as the whole becomes warmer, and the chilled part is
* Genie Industriel, 1864, p. 167.
542 ALUMINIUM.
stirred in that remaining melted, the mass gradually warms up
as the copper combines with the aluminium, until towards the
end the crucible is raised to a white heat by the heat set free
within it. This phenomenon can only be explained on the
basis of chemical action and combination between the two
metals.
4. If a piece of aluminium bronze is heated nearly to its
melting point and hammered at that temperature, it splits into
fragments showing peculiar cleavage planes. These particles
are evidently crystalline, and are smaller the nearer the temper-
ature has been brought to the melting point. If they are ana-
lyzed it will be found that they are all identical in composition
with the mass, and that therefore no liquation or separation of
any kind has taken place. If the bronze were a mere mixture,
the temperature to which these pieces were heated would have
caused the more easily fusible aluminium to sweat out.
Almost all the arguments advanced to prove that the alumin-
ium bronzes are true alloys are along these four lines discussed
by Morin. A German pamphlet describes the 2j^, 5 and 10
per cent, bronzes as not being mixtures, like the alloys of cop-
per and zinc, but perfect combinations of absolute homogeneity
and uniform density, and not altered by remelting. When, how-
ever, it is known that i per cent, or less of aluminium has a
considerable influence on copper, it is almost begging the ques-
tion to claim all the improvement to be due to the formationnof
some alloy in atomic proportion something like Cu^oAl. It is
certain that the first effect of adding the aluminium, and in the
case of very small proportions the whole effect, is that the alu-
minium acts as a deoxidizing agent, somewhat similar to the
action of phosphorus in phosphorizing bronze. It reduces all
dissolved oxides, combines with any occluded gases, and pro-
tects the copper from oxidization during cooling. Thus a frac-
tion of a per cent, of aluminium is of considerable benefit to
brass and bronze, adding just before pouring. I have in mind
the statement of an English metallurgist who reported that on
adding i per cent, of aluminium to a not very pure copper he
ALUMINIUM-COPPER ALLOYS. 543
was unable to find any aluminium on analyzing the resulting
metal, but its properties were a great improvement on those of
the original metal. In this case the aluminium was entirely
slagged off. On adding the same quantity to pure copper it is
certain that a larger part of the aluminium remains in the cop-
per, as is shown by its color, but part of the improvement is
undoubtedly due to the elimination of gases and traces of
impurities.
It is on the strength of these facts that some makers of pure
aluminium have advanced the argument (directed against those
makers producing bronzes directly) that the aluminium forms
valuable bronzes principally by its action on the foreign sub-
stances in the copper, and that therefore a really valuable alu-
minium bronze can only be made by introducing pure alumin-
ium into copper ; that it is wholly wrong practice to reduce an
aluminium bronze of -high percentage to one of low percentage
by adding fregh copper, since, although the bronze used may
be of first quality, yet the already combined aluminium cannot
produce any effect on the copper added, and the resulting
bronze will be of inferior quality. The weak point in this
argument is the last statement, that " the already combined
aluminium cannot produce any effect on the copper added."
We know that the aluminium and copper had previously com-
bined with evolution of much heat, but there is reason to sup-
pose that if subsequently a substance were brought into contact
with this bronze which could be decomposed by aluminium
with the evolution of much more heat than was set free in the
formation of the bronze, the second reaction would take place.
For instance, the reaction
Al,4 3Cu,0-Al,03+3Cu,
is very strongly exothermic, to the amount of something like
270,000 calories, and it is in a high degree probable that the
heat of combination of this amount of aluminium with 9 times
its weight of copper is not more than a small fraction of this
amount. Therefore, the reaction
. 2Cu,Al-l-3Cu,03=Al203+7Cu,
544 ALUMINIUM.
which differs from the former one in involving the decomposi-
tion of the bronze, Cu^Al, is still largely exothermic and there-
fore liable to occur. To sum up, even considering that the
heat developed in the formation of the copper aluminium alloy
is very large, say even 3 or 4 times that of mercury combining
with potassium, the largest so far measured experimentally, yet
it would be so small in comparison with the heat developed by
the reaction of the aluminium on the impurities present as to
theoretically have very little effect in retarding that reaction. I
would therefore conclude that the already combined aluminium
would be very slightly less powerful than free aluminium in re-
ducing and eliminating impurities in the copper, and the prac-
tical effects would be identical.
Further, it is clear that when a considerable percentage of alu-
minium occurs in the bronze, only a part of its beneficial effect
is due to the removal of impurities, a considerable effect being
necessarily produced by the presence of the aluminium in the
bronze. Therefore, even if the argument advanced as to the
combined aluminium not being able to remove impurities were
true, yet this can only be part of the function of the aluminium,
and if the aluminium is really present, the results will be iden-
tical in the two cases as far as the influence of the continued
presence of the aluminium is concerned.
Therefore, it may be safely concluded, that if the bronzes are
made with copper of the same purity, the one made by diluting
a good quality high-priced bronze with copper will be prac-
tically as good as the one made directly from the metals. If it
is true that the bronze placed on the market by those following
the former method is not so good as that made from the metals
directly, the reason is that the high per cent, bronze is not
pure, due to the manner of its production. This is a defect in-
herent in the first production of the alloy, and not chargeable
to the subsequent inability of the aluminium to perform its
function during dilution.
The company producing bronzes by direct reduction have
been understood to claim that since their alloy is made by cop-
ALUMINIUM-COPPER ALLOYS. 545
per or copper vapor absorbing aluminium vapor, the result is a
bronze far more homogeneous than is produced by melting the
two metals together. This is partially true, since the metals in
the latter case may not be kept molten long enough for com-
plete combination to take place, and therefore would lack hom-
ogeneity to a certain degree if not carefully made. This oppor-
tunity for carelessness to enter into the question and affect the
result does not occur in the reduction process, and the latter
bronze would for this reason be at an advantage. But if the
alloy is made carefully and with the precautions dictated by ex-
perience in melting the metals together, there is no reason why
the bronzes should differ. Two specimens containing nothing
but aluminium and copper in like proportions will be identical,
no matter how they are produced.
Looking at the industrial side of the question, it is safe to
say that users of bronze generally prefer to buy the constituent
metals and make their own mixtures in whatever proportions
their experience shows to be best for the kind of work they ex-
ecute. Other things being equal, I think a bronze worker
would prefer to purchase the metals, rather than buy the
bronze ready-made, as in the former case he can always be sure
of the composition of his alloy, and can profit by all those little
variations in the manipulations and in the proportions of metals
used which experience suggests, and which form so valuable a
part of the successful metal-worker's art.
Preparing the bronzes. — In making aluminium-copper alloys
great attention must be paid to the quality of the copper used.
Ordinary commercial copper may contain small amounts of an-
timony, arsenic, or iron, which the aluminium can in no way
remove, and which affect very injuriously the quality of the
bronze. The aluminium bronzes seem to be extremely sensi-
tive to the above metals, particularly to iron. This necessi-
tates the employment of the very purest copper ; electrolytic is
sometimes used when not too high priced, but Lake Superior
is generally found satisfactory enough. Even the purest cop-
per may contain dissolved cuprous oxide or occluded gases,
35
546 ALUMINIUM.
and it is one of the functions of the aluminium to reduce these
oxides and gases, forming slag which rises to the surface and
leaving the bronze free from their influences. If tin occurs in
the copper, it lowers very greatly the ductility and strength
of the bronzes, but zinc is not so harmful.
Care should also be taken as to the purity of the aluminium
used, though its impurities are not so harmful as they would be
if occurring in similar percentage in the copper, since so much
more copper than aluminium is used in these alloys. Yet, the
bronzes are so sensitive to the presence of iron that an alumin-
ium with as small a percentage of this metal as possible should
be used. The silicon in commercial aluminium is not so harm-
ful as the iron, but it does harden the bronze considerably and
increases its tensile strength. The purest aluminium alloyed
with the purest copper always produces the highest quality of
bronze.
The " Magnesium und Aluminium Fabrik," of Hemelingen,
gives the following directions for preparing the bronzes : " Melt
the copper in a plumbago crucible and heat it somewhat hotter
than its melting point. When quite fluid and the surface clean,
sticks of aluminium of a suitable size are taken in tongs and
pushed down under the surface, thus protecting the aluminium
from oxidizing. The first effect is necessarily to chill the cop-
per more or less in contact with the aluminium ; but if the cop-
per was at a good heat to start with, the chilled part is speedily
dissolved and the aluminium attacked. The chemical action of
the aluminium is then shown by a rise in temperature which
may even reach a white heat; considerable commotion may
take place at first, but this gradually subsides. When the re-
quired amount of aluminium has been introduced, the bronze
is let alone for a few minutes and then well stirred, taking care
not to rub or scrape the sides of the crucible. By the stirring,
the slag, which commenced to rise even during the alloying, is
brought almost entirely to the surface. The crucible is then
taken out of the furnace, the slag removed from the surface
with a skimmer, the melt again stirred to bring up what little
ALUMINIUM-COPPER ALLOYS. 547
slag may still remain in it, and is then ready for casting. It is
very injurious to leave it longer in the fire than is absolutely
necessary; also, any flux is unnecessary, the bronze needing
only to be covered with charcoal powder. The particular
point to be attended to in melting these bronzes is to handle as
quickly as possible when once melted."
As with ordinary brass and bronze, two or three remeltings
are needed before the combination of the metals appeajrs to be
perfect and the bronze takes on its best quahties. When the
alloy is thus made perfect, the bronze is not altered by remelt-
ing, and the aluminium, which in the first instance removed the
dissolved oxides and occluded gases from the copper, now pre-
vents the copper from taking them up again and so keeps the
bronze up to quality. If, however, the bronze is kept melted a
long time, and subject to oxidizing influences, the tendency of
the copper to absorb oxygen will cause some loss of aluminium
by the action of the latter in removing the oxygen taken up,
and a slag consisting principally of alumina will result; but if
the remelting of the bronze is done quickly and the surface
covered with charcoal or coke, the loss from this cause will be
very trifling, and the percentage of aluminium will remain prac-
tically constant.
We have already discussed at length the dilution of a high
per cent, bronze to a lower one. This operation is practised on
a large scale by the companies which produce aluminium
bronze directly in their reduction furnaces. I understand that
they simply melt the high per cent, bronze in a crucible and
stir into it pure copper in the required proportions, or else
melt the two down together on the hearth of a reverberatory
furnace. The combined aluminium thus cleanses the added
copper and produces a lower bronze of right quality if the
high-per cent, bronze used is pure and the copper added of the
proper quality. It is, of course, quite certain that no difficulty
can occur in adding aluminium to a low-per cent, bronze to in-
crease its percentage, other than that of imperfect combination,
which may be overcome by one or two remeltings.
548 ALUMINIUM.
Fusibility. — The bronzes all melt easier than copper. Le-
Verrier gives the following determinaticyis with the Le Chatelier
pyrometer :
Aluminium. Copper. Melting point,
o loo 1054° C.
5 95 1030"
7.5 92.5 1000°
10. 90. 1029°
These alloys all become slightly pasty below the melting
point of copper until they have become thoroughly alloyed,
showing that if not carefully prepared they contain free copper.
When re-melted, this disappears, and the combination may be
regarded as perfect.
Casting. — Aluminium bronze is not an easy metal to cast per-
fectly until the moulder is familiar with its peculiarities. The
great enemies of steel castings, dissolved oxides and gases, form-
ing blowholes, are here absent. As we have seen, the alumin-
ium removes these impurities from the original copper, and by
its presence afterwards keeps the bronze free from them. This
difficulty, therefore, is not met in casting aluminium bronze,
but the obstacles which afford the most trouble are the shrink-
age in setting and contraction in cooling. These two factors
are extraordinarily large, and must be met by provisions made
in moulding, as shown later.
A plumbago crucible, or one lined with magnesite (see p.
444), is the best to use for melting the bronze, the melt being
kept covered with powdered charcoal. I would recommend
that the stirrers and skimmers used be coated with a wash made
of plumbago and a little fire-clay, as the contact of bronze with
bare iron tools cannot but injure its quality. The crucible
should not be kept in the fire any longer than is absolutely re-
quired to bring the bronze to proper heat for casting. In cast-
ing, it is of considerable advantage to use a casting ladle, into
which the bronze is poured, which is arranged so as to tap from
the bottom. This efifectually keeps any slag or scum from be-
ing entangled in the casting. The same result is also obtained
ALUMINIUM-COPPER ALLOYS. 549
by arranging a large basin on top of the pouring gate, which is
temporarily closed by an iron or clay stopper. Enough bronze
is then poured into this basin to fill the mould, and after the dirt
is all well up to the surface the plug is withdrawn and the mould
fills with clean metal. For very small work the ordinary skim-
gate will answer the above purpose ; for large castings the tap-
ping ladle is preferred. Plain castings, such as pump-rods,
shafting, etc., and especially billets for rolling and drawing, are
cast advantageously in iron moulds, which should be provided
with a large sinking-head on top to feed the casting as it cools.
Rubbing with a mixture of plumbago, kaoHn and oil is said to
protect the iron moulds from sticking. The chilling makes the
bronze soft, and the slabs and cylinders thus cast for rolHng and
drawing are in good condition to be worked at once. For ordi-
nary foundry castings, sand-moulds are used. The slower cool-
ing makes the castings more or less hard ; if soft castings are
wanted they can be subsequently annealed.
Thomas D. West, the author of " American Foundry Prac-
tice," read a paper on " Casting Aluminium Bronze and other
Strong Metals," before the American Society of Mechanical
Engineers, November, 1886, from which we make the following
extracts :
" The difficulties which beset the casting of aluminium bronze
are in some respects similar to those which were encountered
in perfecting methods for casting steel. There is much small
work which can be successfully cast by methods used in the
ordinary moulding of cast-iron, but in peculiarly proportioned
and in large bronze castings other means and extra display of
skill and judgment will be generally required. In strong
metals there appears to be a " red shortness," or degree of
temperatui-e after it becomes solidified, at which it may be torn
apart if it meets a very little resistance to its contraction, and
the separation may be such as cannot be detected by the eye,
but will be made known only when pressure is put upon the cast-
ing. To overcome this evil and to make allowances for sufficient
freedom in contraction, much judgment will often be required.
550 ALUMINIUM.
and different modes must be adopted to suit varying conditions.
One factor often met with is that of the incompressibility of
cores or parts forming the interior portion of castings, while
another is the resistance which flanges, etc., upon an exterior
surface oppose to freedom of contraction of the mass. The
core must generally be ' rotten' and of a yielding character.
This is obtained by using rosin in coarse sand, and filling the
core as full of cinders and large vent-holes as possible, and by
not using any core rods of iron. The rosin would cause the
core when heated to become soft, and would make it very nearly
as compressible as a ' green-sand' core when the pressure of the
contraction of the metal would come upon it.
" By means of dried rosin or green-sand cores we were able
to meet almost any difficulties which might arise in ordinary
work from the evils of contraction, so far as cores were con-
cerned. For large cylinders or castings which might require
large round cores which could be ' swept,' a hay-rope wound
around a core barrel would often prove an excellent yielding
backing, and allow freedom for contraction sufficient to insure
no rents or invisible strain in the body of the casting. To pro-
vide means for freedom in the contraction of exterior portions
of castings, which may be supposed to offer resistance sufficient
to cause an injury, different methods will have to be employed
in almost every new form of such patterns. It may be that
conditions will permit the mould to be of a sufficiently yielding
character, and again it may be necessary to dig away portions
of the mould or loosen bolts, etc., as soon as the liquid metal
is thought to have solidified. In any metal there may be in-
visible rents or strains left in a casting through tension when
cooling, sufficient to make it fragile or crack of its own accord,
and it is an element which from its very deceptive nature
should command the closest attention of all interested in the
manufacture of castings.
" Like contraction, the element of shrinkage is often found
seriously to impede the attaining of perfect castings from
strong metals. In steel castings much labor has to be ex-
ALUMINIUM-COPPER ALLOYS. SSI
pended in providing risers sufficient to ' feed solid ' or prevent
'draw-holes' from being formed, and in casting aluminium
bronze a similar necessity is found. The only way to insure
against the evils of shrinkage in this metal was to have the
' risers ' larger than the body or part of the castings which they
were intended to ' feed.' The feeder or riser being the largest
body, it will, of course, remain fluid longer than the casting,
and, as in cast-iron, that part which solidifies first will draw
from the nearest uppermost fluid body, and thus leave holes in
the part which remains longest fluid. The above principle will
be seen to be effective in obtaining the end sought. It is to be
remembered that it is not practical to ' churn ' this bronze, as is
done with cast-iron. A long cast-iron roll, i foot in diameter,
can by means of a feeder S inches in diameter and a y^ inch
wrought-iron rod be made perfectly sound for its full length.
To cast such a solid in bronze, the feeding head should be at
least as large as the diamater of the roll, and the casting
moulded about one-quarter longer than the length of roll de-
sired. The extra length would contain the shrinkage hole, and
when cut off a solid casting would be left. This is a plan often
practised in the making of guns, etc., in cast-iron, and is done
partly to insure against the inability of many moulders to feed
solid, and to save that labor. A method which the writer
found to work well in assisting to avoid shrinkage in ordinary
castings in aluminium bronze was to ' gate ' a mould so that it
could be filled or poured as quickly as possible, and to have
the metal as dull as it would flow to warrant a full run casting.
By this plan very disproportionate castings were made without
feeders on the heavier parts, and upon which draw or shrinkage
holes would surely have appeared had the metal been poured
hot.
" The metal works well in our ordinary moulding sands and
• peels ' extra well. As a general thing, disproportionate cast-
ings weighing over loo pounds are best made in 'dry' instead
of ' green ' sand moulds, as such will permit of cleaner work
and a duller pouring of the metal, for in this method there is
SS2 ALUMINIUM.
not that dampness which is given off from a green-sand mould
and which is so liable to cause ' cold shots.' When the posi-
tion of the casting work will permit, many forms which are pro-
portionate in thickness can be well made in green-sand by
coating the surface of the moulds and gates with ' silver lead '
or plumbago.
"From 'blow-holes,' which are another characteristic ele-
ment likely to exist in strong metals, it can be said that alu-
minium bronze is free. Should any exist it is the fault of the
moulder or his mould, as the metal itself runs in iron moulds
as sound and close as gold. Sand moulds to procure good
work must be well vented, and, if of ' dry-sand,' thoroughly
open sand mixture should be used and well dried. The sand
for • green-sand ' work is best fine, similar to what will work
well for brass feastings. For 'dry-sand' work the mixture
should be as open in nature as possible, and, for blacking the
mould, use the same mixtures as are found to work well with
cast-iron."
In view of the above-recommended precautions, the reader
recognizes at once the falsity of the statement in the pamphlet
of a German manufacturer that " aluminium bronze shrinks
almost none at all." I have, in fact, measured the contraction
of a 5 per cent, bronze as y^ inch to the foot, just twice that of
cast-iron. Such wild statements at a time when aluminium
bronze is coming into such extended use, can only bring dis-
credit on the firm making them.
Color. — One per cent, of aluminium changes the color of cop-
per considerably, making it like red brass. The influence of
the aluminium is properly seen when two ingots, one of pure
copper and the other of the bronze, are chilled from a high
temperature, in which case the yellower color of the latter is
plainly perceptible. If, however, the two ingots are let cool
slowly in the air, the effect of the aluminium is more striking,
since the copper oxidizes so as to turn quite black, while the
bronze keeps as untarnished as if it had been chilled in water.
Two and one-half per cent, of aluminium makes a bronze re-
ALUMINIUM-COPPER ALLOYS. 553
sembling in color gold of low carat alloyed with copp^. The
five per cent, bronze is pure yellow and the nearest approach
to the color of pure gold of any known metal or alloy. The
seven and one-half per cent, bronze has the color of the jewel-
er's green gold. The ten per cent, bronze, or aluminium
bronze proper, is a bright light-yellow, similar to the jeweler's
pale gold. The eleven per cent, bronze is still paler. Fifteen
per cent, makes a yellowish-white alloy which is too brittle to
be of any practical use.
Specific gravity. — The aluminium bronzes are not as much
lighter than copper as the percentage of aluminium would indi-
cate. If the specific gravity of a mixture of copper and alu-
minium in the given proportions is calculated, it will be found
uniformly lower than the observed specific gravities, showing
the amount oi contraction in alloying to be large. This will
account for the denseness and very close grain of these bronzes'
The following table will set forth these data more plainly: —
Contraction in
alloying
Percent, ef aluminium. Observed. Calculated. (percent.)
2y„ 8.60* 8.40 2.3
3 8.69 8.33 4.1
4 8.62 8.13 5.7
5
Specific
GRAVITY.
Observed.
Calculated.
8.60*
8.40
8.69
8.33
8.62
8.13
/8-37
8.0
1 8.20*
8.0
S.oot
7.60
/7-69
I 7.56!
7-25
7-25
7-23t
7.10
4-4 \
2.4 i
2.4
71^ S.oot 7.60 5.0
S
4-
1.8
:i}
Hardness. — Accurate observations of the hardness of the alu-
minium bronzes are wanting, with perhaps a single exception.
It is known that the annealed metal, which has been chilled
from a red heat, is much softer than that which has been al-
lowed to cool very slowly. The metal which has been worked
some time becomes almost as hard as steel. I think that the
* According to Saarburger.
t Cowles Bros.' alloys. The rest were given by Bell Bros.
554 ALUMINIUM.
pure aluminium bronzes, when softened, are yet harder than all
ordinary bronzes.
The Cowles Company's bronzes almost invariably contain a
small amount of silicon, which slightly increases the tensile
strength, but is principally active in increasing the hardness of
the bronze. For this reason, the following determinations,
made on their alloys at the Washington Navy Yard, graded ac-
cording to the government standard of hardness, must be con-
sidered as maximum figures: —
Metal. Hardness. Remarks.
Average of gun-steel forgings, oil-
tempered and annealed 21.4 Elongation 20 per cent.
Same, not oil-tempered and annealed 14.9 " 18.7 "
II pec cent, aluminium bronze, cast
in sand 20.0 Elongation 4.5 per cent.
Same, forged at low redness 18.0 " 5.2 "
Same, rolled at red heat 21.2 " 6.5 "
7)'2 per cent, aluminium bronze, rolled
hot 16.9 Elongation 30.0 per cent.
Same, cast in chill moulds ■< •''^ •' '
t.li.8 " 26.1 "
Government bronzes i 3-3 Elongation 1 2.5 per cent.
t. 6.6 " 33.6 "
Transverse strength. — The transverse strength or rigidity of
aluminium bronze is one of its most noticeable qualities.
Strange measured the amount of deflection in bars of aluminium
bronze, gun-bronze, and ordinary yellow brass, laid on horizon-
tal supports with the weight in the centre. From these exper-
iments he concluded that the aluminium alloy was three times
as rigid as gun-bronze and forty-four times as much so as
ordinary brass.
Compressive strength. — Mr. Anderson made a test of alumin-
ium bronze for compressive strength in the Royal Gun Foundry
at Woolwich. The piece taken had a height and diameter of
15 millimeters (tV inch). The results were as follows:
ALUMINIUM- COPPER ALLOYS. SS5
Strain Applied.
' * N Shortening, Permanent set.
Kilos per sq. mm. Lbs. per sq. in. per cent. per cent.
14-84 21,100 I.OI 0.17
96.42 I37.'40 (Specimen crushed.)
It is seen from this test that the elastic limit for compression
is comparatively low, but that the metal give's very slowly, as is
shown by the large interval between this point and the ultimate
crushing strength.
According to two tests made at the Watertown Arsenal on
Cowles' bronzes, their compressive strength was as follows : —
1 1 per cent, aluminium 160,400 lbs per sq. inch.
10 " aluminium 1 53,600 " "
The test pieces being 2 inches long and 5^ inch in diameter,
and cast specimens. The shortening up to the crushing point
was 15 and 23.7 per cent, respectively.
Tensile strength. — One of the first properties of the alumin-
ium bronzes to draw attention to them was their great tensile
strength. Since this property is attended by a large extensi-
bility under strain, and a high elastic limit, we see that they are
very valuable metals fqr engineering uses. For such uses,
however, a metal costing $1.50 to $2 per . lb. was almost
entirely out of question, and it is only recently that the lower
"price has permitted placing the metal in situations where its
great strength is of most use.
Taking the various determinations chronologically, we have,
first, those made by Lechatelier, in 1858. The alloy was cast
in cylinders 10 millimetres (0.37 inch) in diameter, length of
test pieces not given. The results were as follows : —
Strength.
Percentage of ' * ^
aluminium. Kilos per sq. m. m. Lbs. per sq. in.
10 58.36 83,000
10 55-35 78,720
8 33.18 47.190
5 32-20 45,800
S 31-43 44,700
French wrought-iron 35-00 49,780
5S6 ALUMINIUM.
Deville determined the strength of aluminium bronze drawn
into wire, compared with that of iron and steel wire of the same
size (i mm. diameter=No. 19 B. W. G.), as —
Kilos per sq. m. m. Lbs. per sq. in.
Aluminium bronze 85 120,900
Best iron : 60 85,340
90 / 128,000
142,000
Steel { ,S {
Experiments made in 1861,* on the relative strength of alu-
minium bronze and the common metals gave —
Aluminium bronze 19
Gun metal (copper 89, tin 1 1) 10
Drawn brass wire 8
Drawn copper wire 7
Tin bronze (copper 96, tin 4) 4
Same, with I per cent, aluminium 10
Same, with 2 " " l6
In 1862, Anderson tested the strength of aluminium bronze
at the Woolwich Arsenal — testing pieces 3)^ inches long and
0.6 inch diameter, with the following results : —
Lbs. per sq. in.
Aluminium bronze 73,185
Gun metal 3S>ooo
Hardest steel 1 18,000
Medium cast-steel 82,850
Steel from a Krupp cannon 74,670
The Cowles bronzes have been tested officially at the Water-
town Arsenal and at the Washington Navy Yard, with especial
reference to their comparison with the government bronzes.
The Cowles alloys contain small variable quantities of silicon and
the following content of aluminium : —
Grade.
Special "A" 11 per cent.
A 10 "
B 7>t "
C- 5-S'A "
D 2% "
E iM "
* Chemical News, v, p. 318.
ALUMINIUM-COPPER ALLOYS. 557
Three tests of the " Special A" grade, made on the Water-
town testing machine, gave the following results : —
1. Cast in sand Test pieces 2 inches long, 0.2 sq. inch area.
2. Forged hot (some flaws). " lo " 0.5 " "
3. Rolled hot " 2 " 0.2 " "
1. i. 3.
Tensile strength (lbs. per sq. in,). 109,800 87,600 111,400
Elastic limit " « . 79,900 41,000 84,000
Total elongation (per cent.) o. 2. 6.5
Modulus of elasticity 17,240,000 15,625,000
The curve of number 3 is given on the diagram (Fig. 45) as A.
Two tests of the "A" grade, on the same machine gave
5- Cast in sand. Test piece i inch long, 0.08 sq. inch area.
6. Forged hot. " 10 inches '' 0.25 " "
5. 0.
Tensile strength (lbs. per sq. in.) 87,510 89,680
Elastic limit " " 50,000
Total elongation (per cent.) 17. 29.7
Modulus of elasticity 15,741,000
The curve of number 6 is marked B on the diagram.
The test of a specimen of Cowles' bronzes of " A 3" grade,
containing 8j4 per cent, of aluminium, made by Professor Un-
win, F. R. S., gave
Tensile strength 82,389 lbs. per sq. in.
Elastic limit 39.738 " "
Elongation 33-26 per cent.
Test pieces 10 inches long and 0.2 sq. inch area.
The B, C, D, and E grades decrease in tensile, transverse,
torsional and . compressive strength, and in elastic limit in the
order in which they are named, but the extensibility increases
as the other properties decrease.
Samples of Cowles' B and C grades, tested by Mr. Edw. D.
Self, at the Stevens Institute, Hoboken, N. J., gave —
B. C.
Tensile strength ( lbs. per sq. in) S 1,680 40,845
Elongation (per cent) • • 4-' ' '-^
S58
ALUMINIUM.
A sample of the D grade, tested on the manufacturers' ma-
chine, gave a strength of 42,770 lbs., with 53 per cent, elonga-
tion.
Lbs.^er
sq. in.
Fig. 45.
Kilos per
sq. m.m.
..--._._ ___._._.___.__-----
' "r" :"j
%20 000 ----------- ~ ~ ,-'-'--*- ^ '■• ^ ^^ -
!:j5ll'!eus: ::::::::::::::
I .'
:: :::;;?':::::::::::::::::
y - —
:z:'i:i---- -- ::::-::::::;-::
90 000 l-f
^:i^H?:!^^^:^;r::i: = i=i--=:
00.000 1 rr T]lT\ 11 .XfflTI
H L -rm
/ :^" —
I' J-ril
Toooo - 112 ::::::::::;:::: ::::
J^Ll Jl 1 Al .Ml *11 L
: I.::::::::::::::::::::::::::
: 2:::::::::::::::::::::::::::
-
Elongation — per cent.
The bronzes made at Neuhausen by the Heroult process
have been tested in Zurich with the following results : —
ALUMINIUM-COPPER ALLOYS. 559
Grade.
D
H
Tensile
Strength.
Per cent.
Kilos per
lbs. per
Elongation,
aluminium.
sq. m.m.
sq. in.
per cent.
7
(35-9
49,200
25.4
■ 38.7
5S,o6o
27-3
1%
38.4
S4,6oo
27.4
40.7
58,320
25-5
' 36.4
51,760
34-3
8
i 45-°
64,000
45-7
(46.3
65.95°
48.4
8>^
48.0
68,270
37-5
f 50.6
72,250
32.9
9
|si.6
73.380
39-2
r\\/
( 52.2
74,240
23-5
9^
|s6.o
79,650
16.1
10
] 5S-3
j 62.1
78,620
88,325
18.5
IO-5
I0I/2
f 59.0
83.915
12.0
j 64.0
91,000
6.3
Professor Tetmayer, under whose supervision the above tests
were made, made a series of bronzes from the pure metals, for
the express purpose of testing, and obtained the following
results: —
Tensile Strength.
Per cent, of
Elongation,
aluminium.
Kilos
per sq. m.m.
Lbs. per sq. in.
per cent.
5K
44
62,580
64.0
»y2
50
71.II5
52.5
9
57-5
81,780
32.
9%
62
88,180
19.
10
64
91,000
II.
II
68
96,720
I.
ii>i
80
113.780
0.5
The annexed diagram (Fig. 46) shows by its curves the va-
riation of tensile strength and elongation of the aluminium
bronzes with the increasing percentage of aluminium, the curves
Cand C being taken from Cowles' advertised guarantee (1889),
the elongation being the minimum and the strength the average
values guaranteed in castings ; H and H' represent the aver-
age values given by Professor Tetmayer for bronzes made by the
Heroult process ; T and T represent Tetmayer's determina-
tions with bronzes made from the pure metals.
56o
ALUMINIUM.
Tensile strength,
lbs. per sq. in.
130.0DB
Fig. 46.
. of aluminium.
Le Chatelier has tested the resistance of 10 per cent, an-
nealed bronze at different temperatures, with the following re-
sults—
Temperature.
Tensile strength.
Elongation
C°
Kilos per sq. m.m.
Pounds per sq. in.
per cent.
15
S3-2
76,000
19
100
52.4
74,800
22
150
51.0
72,800
21
200
49.2
70,200
22
250
47.0
67,000
21
300
44.2
63,000
19
350
37-0
52,800
15
400
23.2
33,000
21
45°
1 0.0
14,200
23
ALUMINIUM-COPPER ALLOYS. 561
These figures show that the bronze retains over three-quar-
ters of its strength up to 300°, and show that it is admirably-
adapted for replacing copper tubes in steam boilers and for
steam pipes.
Annealing and hardening. — Aluminium bronze acts like ordi-
nary brass in these respects. It is softened by chilling; the
best procedure is said to be to heat the articles to bright red-
ness for some time, to destroy all crystalline structure, then cool
in still air to full redness and plunge into cold water. The
metal becomes very hard and stiff when worked for some time
without annealing. To get the bronze to its maximum elasticity
and hardness it must be cooled very slowly. Articles of bronze
can be heated red-hot in charcoal powder and allowed to cool
embedded in it. It is said that the bronze can be thus made
elastic enough for the hair-springs of watches.
Working. — Despite the assertions that aluminium bronze can
be heated to bright redness and then hammered out until quite
cold, yet it is not so easily worked. Persons who have had a
large experience with the alloy say that it possesses peculiarities
in working which must be learned and strictly attended to. As
with many other alloys, there is a certain temperature at which
it works perfectly, but this is contained within narrow limits.
This heat is rather indefinitely stated as full-redness. At a lit-
tle above this heat (bright-red) or at a little below (low-red) it
works with much less ease. If it is rolled at this temperature,
it does not become brittle by working. When the bronzes are
worked cold they will quickly stiffen up, and will crush or
spHt unless annealed frequently. Working increases the
strength and rigidity, but diminishes the extensibility. As alu-
minium bronze is such a strong metal, it is natural to expect
that it would require a large amount of power to work it. This
is the case, and accords with the fact that when Cowles Bros,
first introduced their bronzes the workers of copper and ordi-
nary bronze came very nearly breaking their rolls in endeavor-
ing to work it; the steel workers, however, had no difficulty
from this source. The Aluminium Brass and' Bronze Company,
36
S62 ALUMINIUM.
who work up the Cowles bronzes, have put in rolls which are
even more powerful than those used for working steel bil-
lets of corresponding size. It is recommended to subject the
billet at the first pass to the heaviest presure the rolls will give,
in order to destroy at once any crystalline structure. When
rolling cold, the lower grade bronzes can be worked for a
longer time between annealings, but when rolling hot the
higher bronzes give the least trouble.
When drawing the bronzes, they are first cast into rods of
small diameter, annealed and then drawn. Very hard dies are
required, or the ordinary bronzes, especially the higher grades,
are apt to become so hard between annealings as to cut them.
The speed of drawing must be slow, and the reduction
effected very gradually.
In regard to forging aluminium bronze, the statement that it
can be forged perfectly at all temperatures from bright red to
cold does not coincide with the experience of many workers.
At a cherry red, the suitable temperature for rolling, it hardly
forges at all. A much lower temperature must be used, a low
redness, and at that heat it forges perfectly. Metal hammered
from this heat until it is cold has its strength much increased.
Aluminium bronze can be spun, stamped, or pressed, like
ordinary brass. In these operations it must be annealed after
each successive treatment, since it hardens up so quickly
under the great pressure.
In working with the file it is noticeable that the aluminium
bronzes do not clog the file. Before the chisel it gives long,
clean chips. On the lathe and planing machine the tool takes
off long elastic threads and leaves a fine surface. It is especi-
ally in these cutting operations that the great advantages of a
metal as strong as steel and yet as easy to work as brass be-
come apparent. Simms states that aluminium bronze can be
easily engraved, taking the sharp lines and deep cuts of the
tool as well as any cast metal. Since it can be soldered, it
forms a very suitable material for drawing into tubes. It is
stated that it can even be hammered out into leaf, but this state-
ment needs further proof.
ALUMINIUM- COPPER ALLOYS. 563
Anti-friction qualities. — Along with the great toughness and
malleability of aluminium bronze, as also its fine grain, we note
a peculiar unctuousness or smoothness which seems to resist
abrasion, and to render it one of the best anti-friction metals
known. Morin held that to bring out the metal's best qualities
it should not be used in castings, but as forged or rolled forms.
He cites an instance where it was appHed to the bearings of a
large lathe, the axle having a diameter of 60 millimetres and
making up to 1800 revolutions per minute. A plate of alu-
minium bronze was soldered in place on a common bearing
metal back, and then carefully bored true. This bearing had
been in use four years at the time of Morin's statement, and
after 2^ years' working the wear was only 0.4 millimetre.
Cowles Bros, recommend using the higher grades for bearings
working under very heavy pressures, as their great strength
prevents crushing, while the lower grades are more suitable for
high speeds and low pressures. They recommend casting the
bearings, bringing the working surface up to a high polish and
using them only under steel axles.
An incident occurring under the author's immediate notice
may be more to the point than quotations from other sources.
A smooth metallic ball was required for a rotary steam engine,
to work between steel guides in such a position that almost all
the work of the engine passed through it. Steel balls were
impracticable because they cut the guides. All sorts of
bronzes and anti-friction metals were tried, but a few hours'
work would cut them out of shape. Mr. Joseph Richards sug-
gested to the maker that an aluminium bronze ball be tried.
A ball was cast of ten per cent, bronze, but the casting not be-
ing solid it was warmed up and hammered until all the holes
were closed. The ball was then turned smooth and polished.
On putting into place it was worked several days at high speed
without giving way, and on taking it out for examination the
only sign of wear was that the polish was a little higher. I
think that the hammering increased its capability of resistance,
and would recommend that if the cast aluminium-bronze bear-
564 ALUMINIUM.
ings do not meet any extra requirements put on them, the
hammered or rolled metal might be successfully substituted."
Conductivity. — The aluminium bronzes conduct heat and
electricity better the lower the proportion of aluminium. Benoit
measured the electrical conductivity of 10 per cent, bronze as
13, silver being lOO and copper 90. Edw. D. Self states that
he found the heat conductivity of the 6 per cent, bronze almost
the same as for pure copper, and that of the 10 per cent, bronze
very little less.
Resistance to corrosion. — Deville said, " In chemical proper-
ties aluminium bronze cannot differ much from the other alloys
of copper," yet from numerous experiments we have noticed
that it does resist most chemical agents better, particularly
sea-water and sulphuretted hydrogen.
Bernard S. Proctor,* after describing thirty-one experiments
comparing aluminium bronze and brass, sums up the conclu-
sions as follows : —
" From the above experiments it appears that aluminium
bronze has a little advantage over ordinary brass in power to
withstand corrosion, and its surface, when tarnished, is more
easily cleaned. This should give it general preference where
cost of material is not an important consideration, especially if
strength, lightness and durability are at the same time desirable.
It is out of my power to say anything about its fitness for deli-
cate machinery, except that its chemical examination has re-
vealed nothing which can detract from the preference its me-
chanical superiority should give it. Being so much less acted
on by ammonia and coal-gas suggests its suitability for chem-
ical scales, weights, scoops, etc. Its resistance to the action of
the weather and the ease with which tarnish is removed render
it especially applicable for door-plates, bell-handles, etc. Its
mechanical strength and chemical inactivity together recom-
mend it for hinges exposed to the weather. In experiments
18, 22, etc., the tendency of brass to corrode on the edges and
at any roughness on its surface will be observed, while the
* Chem. News, 1861, vol. iv, p. 59.
ALUMINIUM-COPPER ALLOYS. 565
bronze is free from this defect. In several cases the bronze
seemed to be more quickly covered with a slight tarnish which
did not increase perceptibly, probably the tarnish acting as a
protection to the metal ; but the brass, though less rapidly dis-
colored, continued to be corroded and apparently with in-
creased speed as the action was continued. The bronze is
more easily cleaned. For culinary vessels its superiority to
metals now in use appears questionable." The author states
that he wrote the article with a home-made pen of aluminium
bronze, and suggests that it is well worthy of the attention of
pen-makers.
The Cowles Co. states in a pamphlet that salt-water, soap-
water and urine have no effect on aluminium bronze, which
would make it a very valuable metal for ship builders and sani-
tary engineers. It is well known that the fatty acids, as in tal-
low, corrode brass and bronze, as is seen in old fashioned brass
candle-sticks, but aluminium bronze is said to be untouched by
these agents. It is said that for preserving pans, in which fruit
juices are boiled, aluminium bronze is superior in resisting
power to the coppers now used. Sulphuretted hydrogen and
coal-gas have hardly any effect on it. Hydrochloric acid dis-
solves out the aluminium, nitric acid dissolves out the copper.
Tissier Bros, remarked that the color of the bronzes containing
from 5 to 10 per cent, of aluminium could thus be altered at
will by leaving in dilute nitric or hydrochloric acid. Concen-
trated sulphuric acid attacks it at first, but a coating is speedily
formed which seems to protect the metal against further injury ;
dilute sulphuric acid attacks the alloy more deeply. Hot soda
solution slowly removes the aluminium near the surface, leav-
ing a velvety coating of copper oxide. The acid of perspira-
tion is quite active in attacking aluminium bronze superficially,
as any one can test by noticing how quickly a polished surface
is tarnished. I do not think, however, that the corrosion is
any more marked than other bronzes would show, and the tar-
nish is very easily removed and the polish restored by a little
rubbing with a dry woolen cloth.
566 ALUMINIUM.
In order to test the suitability of aluminium bronze for boats,
the following experiments were made at Neuhausen. Sheets
of the metals were kept for 40 hours in ( i ) a solution of 3 per
cent, sodium chloride and 4 per cent, acetic acid, (2) in sea-
water. The comparative losses were as follows : —
I. II.
10 per cent. Bronze free from Silicon i i
10 per cent. Bronze with 2.89 per cent. Silicon 2 39
Brass with 3.59 per cent, of aluminium 4 loi
Phosphor Bronze 32 116
When heated in the air, aluminium bronze remains unoxi-
dized even if kept at a red heat for a long time. This is a re-
markable property when contrasted with the behavior of brass
wire, which would quickly turn to oxide. It is stated that it
has been kept at a bright red heat for several months without
showing any oxidation. As a chemist, who has in common
with all other chemists been annoyed by the oxidation of brass
wire when heated over a Bunsen burner, I hope that aluminium
bronze wire gauze will soon be made for this purpose.
When exposed to the weather, the tarnish formed is very
superficial and protects the metal underneath from continued
oxidation. The aluminium bronzes take on a darker hue, after
some exposure, but they never turn black like ordinary
bronzes, or green like brass. Since the color of out-door
bronze statues is only preserved by a coat of lacquer, which
hides many of the most artistic strokes, the value of a bronze
which will stand the weather unprotected should be utilized by
the art casters. It has been proposed to cast cannon of alu-
minium bronze, and this incorrodibility gives it an advantage
over all other bronzes for this purpose. A commission ap-
pointed by the Austrian Government in t888, to report on
various types of rifle barrels, tested, among other materials,
aluminium bronze. Two rifles, one with a steel barrel the other
of aluminium bronze, were left in the gutter on a roof for sev-
eral weeks. On examining them, the steel gun was rusted so
far as to be completely useless, while the bronze barrel was
ALUMINIUM-COPPER ALLOYS. 567
only slightly tarnished and was loaded and fired without clean-
ing and without accident.
Uses of the aluminium bronzes. — The previous remarks have
necessarily contained allusions to the many uses to which these
bronzes may be advantageously applied. Their resemblance to
gold early caused their use for jewelry, watch-chains, etc., but
the ease with which their fine polish is tarnished by perspira-
tion makes them unsuitable in this direction. Their wearing
qualities make them valuable bearing metals, being also espec-
ially applicable to parts of machinery subject to heaxy strain
and rapid work, such as weavers' shuttles, ball-bearings, pin
pivots, etc. It seems to be the great strength united with con-
siderable malleability which gives these wonderful wearing
qualities.
The Engineering and Mining Journal * suggested that alu-
minium bronze should make excellent battery, sizing and jig-
screens for mining and ore working machinery. The Cowles
Company soon afterwards placed milling screens of 5 per cent,
bronze on the market, and they have given excellent satisfac-
tion. Screens of this bronze lasted six months, while Russia-
iron screens broke through in two weeks.
The considerable resistance of aluminium bronze to chemical
agents has suggested its use as a material for pumps and
machinery subjected to the action of acid mine-water. It is
said that the Worthington Company have used it in their high
pressure mine-pumps.
Mr. Strange.t an English engineer, made a thorough discus-
sion of the suitability of aluminium bronze for the construction
of astronomical and philosophical instruments, and concluded
that it was superior not only in some, but in all respects to
any metal hitherto used for that purpose.
Mr. A. H. Cowles read a paper before the U. S. Naval Insti-
tute, October 27, 1887, urging the merits of aluminium bronze
♦August, 1887.
t Chemical News, vii., p. 220.
568 ALUMINIUM.
as a metal for casting heavy guns. Reference was made to the
casting of a mountain howitzer of this bronze in i860, which
stood every test put upon it by the French artillery ofiScers,
and which would have caused a revolution in cannon material
but for the fact that its cost was prohibitory. The principal
points made by Mr. Cowles are — i. The great strength and
high elastic limit of aluminium bronze. 2. Its ductility. 3.
The sound castings it produces. 4. The fact that no liqua-
tion takes place during cooling, as in ordinary gun bronze.
5. No tendency to crystallization, as is the case with steel.
6. No rusting or corrosion. 7. Seventy per cent, of the cost
of the gun is represented by the metal, which may be melted
over when the gun is worn out. 8. Even with this high cost of
metal, the total cost of the gun would be only four-fifths that
of a built-up steel gun. While the discussion following the
reading of this paper was not altogether in favor of the solid
gun versus the built-up gun, yet no doubt was expressed that
for casting solid guns aluminium bronze was undoubtedly the
best metal that could be used, and as regards its comparison
with built-up steel guns, the sum total of the discussion seemed
to point to the expectancy that the bronze gun would be as
good, if not better. But, as Deville was wont to say, " It is not
necessary to theorize if you can make the experiment," and we
hope soon to see a large aluminium-bronze cannon success-
fully cast and its exact worth demonstrated.
Aluminium bronze has been used very advantageously as a
material for propeller blades. Its freedom from galvanic ac-
tion, its non-corrosion by sea water, and its great strength, make
it particularly well adapted for this use. Quite a long discus-
sion on this subject was printed in London Engineering during
April and May, 1888, raised principally by the makers of man-
ganese bronze, but it was shown conclusively that in every
point in which the latter was claimed to be of special advant-
age, aluminium bronze was still more advantageous. The Web-
ster Aluminium Co. cast a propeller for a vessel whose bottom
was subjected to the destructive influence of tropical waters.
ALUMINIUM -COPPER ALLOYS. 569
and it was used with the most satisfactory results as regards
freedom from corrosion. I understand that several of the new
U. S. gunboats have aluminium bronze propellers, since as
speed is a great requisite, the lightening of the blades made
possible by the use of a much stronger metal is of consider-
able advantage.
Besides the items mentioned, we might conclude by saying
that if aluminium bronze were as cheap as brass or ordinary
bronze, there is hardly a single use that can be mentioned for
which it would not be preferred ; since it costs more than these,
it will be used for all those purposes for which it is of partic-
ular excellence, and its use will extend in a largely increasing
proportion as its cost is lowered. Its specific gravity is not so
much lower than ordinary brass or bronze as to cause its use on
this account, but the fact that its superior strength allows a
large decrease in weight without any less strength than with
the other metals, will aid greatly in increasing its sphere of
usefulness. The fact that it will not rust gives it always the
advantage over steel in out-door uses, and the fact that it
can be cast perfectly will cause it to replace complicated steel
forgings.
With aluminium bronze at the prices now made possible by
the low prices of aluminium and copper, it should be able to
drive all other strong bronzes out of the field.
Brazing. — Aluminium bronze can be brazed easily at a red
heat, using ordinary brazing solder (zinc i, copper i) and 3
parts of borax.
Soldering. — Deville stated that aluminium bronze could be
soldered with ordinary hard solder at a low red heat. It re-
sists the common soft solders at ordinary temperatures, but if
some zinc amalgam is added it can be soldered cold.
Schlosser* gives the following directions for preparing this
solder : White solder is alloyed with zinc amalgam in the pro-
portions
White solder 248
Zinc amalgam r ' ' '
*Das L5then, p. 180.
570 ALUMINIUM.
The white solder may be composed as follows: —
Brass 40 22 18
Zinc 2 2 12
Tin 8 4 30
The zinc amalgam is made by melting 2 parts of zinc, adding
I part of mercury, stirring briskly and cooling the amalgam
quickly. It forms a silver white, very brittle alloy. The white
solder is first melted, the finely powdered zinc amalgam added
and the alloy stirred until uniform and poured into bars.
The Cowles Co. recommend the following solders as effective
and convenient for aluminium bronze jewelry: —
Hard solder for 10 per cent bronze — ■
Gold 88.88
Silver 4.68
Copper 6.44
Middling hard solder for 10 per cent, bronze —
Gold 54.40
Silver 27.00
Copper 18.00
Soft solder for Al bronze —
Copper 70 per cent. I -^
Tin 30 " [Bronze 14.30
Gold 14.30
Silver 57-10
Copper 14-30
The aluminium bronzes can be easily brazed, using borax or
borax and cryolite as a flux. A cheap bronzing solder is an
alloy of equal parts of zinc and copper, or 46 parts zinc, 52
copper and 2 tin. Butt and lapped joints made in this way are
from one-half to one-third as strong as the bronze itself, and
stand hammering or rolling.
Silicon-aluminium bronze. — Cowles Bros, have, by reduciffg
fire-clay in presence of copper, obtained alloys of aluminium,
silicon and copper. This alloy is white and brittle jf it contains ,
ALUMINIUM-COPPER ALLOYS. 57 1
over 10 per cent, of aluminium and silicon together. With
from 2 to 6 per cent, of these in equal proportions, the alloy is
stronger than gun metal, is very tough, does not oxidize when
heated in the air, and has a fine color. With 10 per cent, of
aluminium and 2 or 3 per cent, of silicon, Cowles Bros, claim
to have produced one of the strongest metals known.
Phosphor-aluminium bronze. — Thos. Shaw, of Newark, N.J.,*
patents a phosphor-aluminium bronze, making the following
claims : First, an alloy of copper, aluminium and phosphorus,
containing 0.33 to 5 per cent, of aluminium, 0.05 to i per cent,
of phosphorus, and the remainder copper. Second, its manu-
facture by melting a bath of copper, adding to it aluminium in
the proportions stated, the bath being covered with a layer of
palm oil to prevent oxidation, and then adding a small propor-
tion of phosphorus.
It has been stated that thfs alloy has a high conductivity (pre-
sumably for electricity), but I am unable to find any determi-
nations or evidence of any kind to substantiate this statement.
Boron-aluminium bronze. H. N. Warren, of Liverpool, Eng-
land, produces first alloys of aluminium with boron (see p. 498).
These crystalline, brittle alloys are then dissolved in copper to the
extent of 5 or ID per cent. The bronze produced is described
as melting sharply, casting well, and showing no signs of liqua-
tion. No information has been given as to its mechanical
properties.
* U. S. Patent, 303,236, Aug., 1884.
CHAPTER XVI.
ALUMINIUM-IRON ALLOYS.
Although aluminium does not appear to combine as ener-
getically with iron as with copper, yet the affinity between
these two metals is sufficient to cause their combination in all
proportions. The useful alloys, however, are confined to those
containing a small amount of aluminium, the addition of
small quantities of iron to aluminium producing no useful
result.
Iron is one of the most obstinate impurities in commercial
aluminium. About the only way to obtain aluminium free from
iron is to keep the materials from which it is made scrupulously
free from that metal, since if it once gets into the aluminium, it
is almost impossible to remove it. As to its exact influence on
the properties of aluminium, when in small quantities, we may
say that it renders the color more of a gray, the aluminium
becomes harder, less malleable, and appears to crystallize more
readily. The most noticeable effect, however, is on the fusi-
bility. Tissier Bros, observed, somewhere about 1857, that
aluminium free from iron could be melted on a plate of alu-
minium containing 4 to 5 per cent, of that metal. Deville also
observed that if a large amount of iron was present (10 per
cent.), the aluminium could be liquated by careful heating, a
ferruginous skeleton remaining, while aluminium containing less
iron flowed away. This process, however, could not be used
for the ultimate purification of commercial aluminium, since
when the percentage of iron is low no liquation takes place.
The exact rise in the melting point due to the presence of iron
has been recently determined by Prof. Carnelly. He found
that a specimen of aluminium containing 0.5 per cent, of iron
melted very close to 70o°C., whereas a specimen containing 5
(572)
ALUMINIUM-IRON ALLOYS. 573
per cent, of iron did not even soften at that temperature, but
commenced to fuse at about 730°.* The effect of the iron is
particularly seen in rendering the fusion pasty. Since silicon
acts in an almost similar manner, it is important to observe that
commercial aluminium can contain a certain small quantity of
iron with very little detriment only on condition that the amount
of silicon present is small.
Tissier Bros, took pure aluminium in small pieces, mixed it
with bits of pure iron wire, and melted in a crucible under
common salt. The alloy with 5 per cent, of iron thus made
was harder, more brittle, and less fusible than pure aluminium.
The alloy with 7 per cent, of iron differed from the preceding
principally in showing a stronger tendency to crystallize. With
8 per cent, of iron the alloy crystallized in long needles. Deville
states that the alloy containing 10 per cent, of iron has the
color and brittleness of native antimony sulphide (stibnite).
By melting together 10 parts of aluminium, 5 parts of ferric
chloride, and 10 parts each of potassium and sodium chlorides,
Michel obtained a crystalline mass, which by careful treatment
with very dilute hydrochloric acid left some six-sided crystals,
having the color of iron, and agreeing nearly to the formula
AljFe, containing 51 per cent, of iron.f These crystals dis-
solved easily in hydrochloric acid ; caustic soda dissolved out
the aluminium. Calvert and Johnson obtained the alloy AljFcj
(see p. 420), containing on analysis 24.55 P^*" cent, of alumin-
ium— the formula calling for 24.34 per cent. Globules of this
alloy were white, did not rust in moist air, and when treated
with weak sulphuric acid gave up the iron, while the aluminium
remained as a skeleton, having the shape of the original button.
These experimenters also obtained an alloy containing, in two
different experiments, 12.00 and 12.09 P^'' cent, of aluminium.
The formula AlFe,, requires 10.76 per cent. This alloy was
extremely hard, and rusted on exposure to the air ; but could
be forged and welded.
* These temperatures are both too high, which does not, however, affect the com-
parison.
f Ann. der Chemie und Pharm., 1 1 J, 102.
574 ALUMINIUM.
The iron-aluminium alloy which is being largely used at
present for introducing aluminium into iron and steel is gen-
erally made with 5 to 15 per cent, of aluminium and has re-
ceived the trade name of "ferro-aluminium." Several different
makes of this alloy are on the market, some made directly
from alumina, others made by adding aluminium to iron. An
analysis of Cowles Company's ferro-aluminium has already been
given. The grade mostly supplied by this company averages 6
to 9 per cent, of aluminium, with 2^ to 3 J^ per cent, of silicon,
and about 3 per cent, of carbon. When ferro-aluminium is
made by alloying aluminium with iron, a good quality of pig-
iron is chosen, and when melted the aluminium, in bars, is
seized in tongs and dipped under the surface. A rise of tem-
perature occurs, and a noticeable separation of graphitic car-
bon, causing " kish" to collect on the surface. It is said that
the pig-iron thus alloyed has its combined carbon almost en-
tirely converted into free carbon, losing sometimes as much as
2^ per cent, in weight thereby. When all the aluminium re-
quired has been added, the melt is stirred, the crucible remain-
ing in the furnace ; then it is let stand for a few minutes, taken
out of the fire, skimmed clean and cast into slabs or bars.
These alloys (ferro-aluminiums) are very hard, brittle, easily
broken, and yellowish-white in- color. Ledebuhr states that as
the percentage of aluminium increases the iron becomes less
magnetic, and at 17 per cent, the alloy is non-magnetic. It is
said that in the works where the alloy is being made a workman
can, after a few practices, grade the alloys roughly by a sim-
ple magnetic test, even some degree of accuracy being finally
attainable. Since wrought-iron and steel are very sensitive to
small amounts of impurities, it is important that the ferro-alu-
minium added to them should be as pure as possible, being
made from the purest pig-iron ; this condition is of less im-
portance when operating on cast-iron. This has led to the
manufacture of two grades of ferro-aluminium, one for ordinary
foundry use, the other for steel and mitis-castings.
Pig-irons and commercial iron and steel do not take up any
ALUMINIUM-IRON ALLOYS. 57$,
appreciable quantity of aluminium in the process. of their manu-
facture. Blair states that he finds aluminium nearly always
present as such in steels, but only in quantities of a few thous-
andths of a per cent, such as, from actual analyses, 0.026,
0.029, 0-034 per cent. Corbin reported 2.38 per cent, in
chrome steel, but Blair finds chrome steel to contain no more
aluminium than other steels. Aluminium is very seldom re-
ported even in the smallest amount in wrought-iron, since the
puddHng process may be reasonably expected to eliminate al-
most entirely any that might be in the pig-iron. Conflicting
views have been expressed as to the presence of aluminium in
pig-iron, As much as i per cent, has been reported in Ger-
man gray-iron ; Griiner states that some English pig-irons con-
tain 0.5 to I per cent., and some Swedish irons 0.75 per cent.
Percy quotes an analysis of pig-iron showing 0.97 per cent, of
aluminium, but questions its correctness, supposing that much
of this might have come from aluminium contained in included
slag. The Marshall furnace, at Newport, Pa., has produced
iron containing as much as 0.9 per cent, of aluminium, working
with a slag carrying 25 per cent, of alumina. (See p. 428.)
Faraday and Stodart obtained an alloy containing 3.41 per
cent, of aluminium by melting an iron carbide with alumina at
a very high heat. This alloy is described as being white, close-
grained and very brittle. G. H. Billings (see p. 424) made an
alloy containing 0.52 per cent, of aluminium and 0.2 per cent,
of carbon. Its fracture showed solid, homogeneous and finely
crystalline, like steel with i per cent, of carbon. It forged very
well at cherry redness, but crumbled to fragments at a yellow
heat; it would not harden.
As the principal use of aluminium in iron is as a refining
agent, we will sub-divide the remainder of this chapter into
three parts ; namely, the effect of small quantities of aluminium
on (i) steel, (2) wrought-iron, (3) cast-iron.
Effect of Aluminium on Steel.
Although A. A. Blair found aluminium almost always present
576 ALUMINIUM.
in steel as a few thousandths of a per cent., yet he was not able
to determine that so small a quantity had any appreciable effect
on the properties of the metal.
Faraday, in seeking for the distinguishing ingredient of the
famous Bombay Wootz-steel, found that it always contained alu--
minium in quantities varying from 0.0128 to 0.0695 psr cent.
In order, then, to prove the case synthetically, Faraday and
Stodart took an alloy of iron with 3.41 per cent, of aluminium
and a little carbon, and melted it in various proportions with
steel. On melting 40 parts of the alloy with 700 of good steel
(introducing 0.18 per cent, of aluminium), a malleable button
was obtained, which on treatment with acid on a polished sur-
face gave the beautiful damask peculiar to Wootz. On melting
67 parts of alloy with 500 steel (introducing 0.4 per cent, of
aluminium) the resulting button forged well, gave the damask,
and " had all the appreciable characteristics of the best Bombay
Wootz." Karsten could not find any aluminium in specimens
of Wootz which he examined, and suggested that that found
by Faraday was due to intermingled slag; but the latter found
aluminium in the steel without silica, which seems to prove
that his results are beyond question.
Rogers* corroborated the above results obtained by Faraday.
He melted an iron-aluminium alloy with steel in quantity suf-
ficient to introduce 0.8 per cent, of aluminium. The product
had great hardness, a bright silver-like polish, and when treated
with dilute acid acid gave the undulating markings peculiar to
Damascus steel and Wootz.
With aluminium costing $12 to $16 per lb. it can be readily
seen that this use could not be practiced commercially ; but,
with aluminium at less than half that price, and especially with
even more economical ferro-aluminium to be had, these old
references were looked up, and many steel-makers began try-
ing the virtues of aluminium. Since 1885 hardly a maker of
crucible steel and steel castings but has made some experi-
* Moniteur Industrie!, 1859, p. 2379.
ALUMINIUM-IRON ALLOYS. 577
mehts in this line. It had long been known that if alumina is
added during the melting of steel in a crucible, the grain and
lustre are improved. It was found that ferro-aluminium, added
just before pouring, had the same efifect ; and since the latter
operation is under exact control, it is preferred to the former
practice, providing that the ferro-aluminium can be obtained
pure enough for this use.
From experiments made at Faustman & Ostberg's Mitis
Foundry at Carlsvick, Sweden, in 1885, it was proved that ferro-
aluminium is of great use in making steel castings, and the pro-
cess was patented by Wittenstrom.* Wrought-iron scrap, was
melted in crucibles, carbonized to hard steel by adding pure
pig-iron, and before pouring, ferro-aluminium added to supply
0.1 per cent, of aluminium. The steel was then cast into the
shape of ordinary edge-tools, which needed only to be hardened
and ground in order to be ready for use. The surface of these
tools was very clean and took a high polish. It was found that
manganese, which is so often purposely introduced into steel,
was deleterious in its action on steel containing aluminium,
and that mild steel almost free from manganese gave by far the
best results when aluminium was added. If true, this is a curi-
ous fact which it is not easy to see the cause of. In Bessemer
practice it is evidently of no use to add ferro-aluminium before
blowing, but it has been thrown into the converter just before
tipping into the ladle, and Mr. Ostberg states that Bessemer
ingots containing only 0.06 per cent, of carbon have been thus
made which did not rise in the mould at all, and were solid and
of good quality throughout. SimHar advantages should also
result on treating Siemens-Martin steel in this way, and perhaps
even greater advantages, since mild steels are so much more dif-
ficult to cast solid than high-carbon steel.
At present aluminium is in general use among steel-casters.
Some add it in the crucible or furnace,, others put it into the
ladle or runner, while others even drop it into the main pour^
*U. S. Patent, 333,373; Dec. 29, 1885, English Patent, 8,269; Ny 3. -1885. ,;
37
5/8 ALUMINIUM.
ing gate of the mould and pour the steel onto it. The latter
method of procedure has been found by far the most econom-
ical, and even superior in efficiency.
The Phoenix Iron Company of Germany report that 0.2 per
cent, of aluminium added (as ferro-aluminium) to their basic
Siemiens-Martin steel gave them a metal with a tensile strength
of 112,000 pounds per square inch, with 12.5 per cent, elonga-
tion, whereas the best results previously attained were never
over 100,000 pounds. Swedish works have found that an addi-
tion of 0.02 to 0.025 per cent, to a Bessemer steel with 0.9 per
cent, of carbon, ensures good castings ; in Martin steel of 0.65
per cent, carbon, o.oi per cent., put into the gate of the moulds,
ensures dense ingots. In the latter steel, when casting ingots
of 400 kilos weight, containing 0.15 per cent, of carbon, and
using no aluminium, a zone of blow-holes was formed about S
centimetres from the sides of the ingot; using 0.02 per cent, of
aluminium, superficial blows appeared in such quantities as to
make the ingot unsalable ; with 0.04 per cent, the ingot was
free from blow-holes and almost faultless.
In general, low carbon steel requires more aluminium to
give sound castings than high carbon metal, Bessemer more
than Siemens-Martin steel, and in any case more aluminium is
required when it is added to the metal in the ladle than when
dropped in small pieces into the flask during the pouring. The
Swiss makers of aluminium, who should be naturally interested
in selling as much aluminium as possible, recommend for steel
the addition of only 0.004 to 0.025 P^r cent. ; for carbonless
iron 0.01 to O.i per cent., the latter being sufficient to quiet
overblown iron which is " wild" in the ladle.
It is also important not to add too much aluminium to steel,
because of the excessive shrinkage any excess causes. In high
carbon steel, any considerable amount of aluminium left over
also decreases its strength by separating out some of the com-
bined carbon as graphite. It is therefore sometimes good
policy to add a little less aluminium than is necessary to com-
pletely eliminate the blow-holes, preferring to have a few of
ALUMINIUM-IRON ALLOYS. 579
these left than to have a large shrinkage cavity. Ingots of alu-
minium-steel have been made, at a time when its use was not
properly understood, which contained a "shrink" clear to the bot-
tom of the ingot. It was hoped that perhaps the use of alu-
minium as a deoxidizer would render manganese unnecessary.
P. A. Gilchrist investigated this point, and found that with alu-
minium alone the steel is red-short, so that while the manga-
nese is less necessary, it is not rendered superfluous.
An interesting effect of the addition of aluminium to soft
steel is the increased ease of welding. Specimens have been
shown by the Cowles Syndicate Co., in England, of iron welded
to Siemens-Martin steel with and without aluminium. With
the ordinary steel the line of weld was clearly visible, but with
steel containing 0.2 per cent, of aluminium no such line could
be seen, the crystalline structure of the iron appearing to merge
gradually into the fine grain of the steel, even under the micro-
scope.
We shall see later that the addition of aluminium to cast-
iron tends to separate combined carbon as graphite. This
probably accounts for the poor results obtained by adding
ferro-aluminium to high carbon steels ; for these, melting more
easily and fluidly than mild steels, would be made less fusible
by the decrease in combined carbon and possibly also made
pasty by graphite being entangled in the metal as it thickens.
As illustrative of this point we will quote the experiments made
by R. W. Davenport.* A large charge of carbonless ingot
iron holding about 0.08 per cent, carbon, and boiling strongly,
was tapped into two similar ladles and ferro-manganese added
in order to convert it into a low-carbon steel. Into one ladle
was put, in addition, ferro-aluminium sufficient to introduce
0.064 per cent, of aluminium. Both ladles were then teemed
into sand castings and ingot moulds. The steel treated with
ferro-aluminium lay perfectly dead and piped in the ingot
moulds, and yielded practically solid sand castings ; the other
* Howe's Metallurgy of Steel.
S8o ALUMINIUM.
rose in the moulds, had to be stoppered, and gave very porous
sand castings. On another occasion, ferro-aluminium sufficient
to introduce 0.04 per cent, of aluminium and O.IO per cent, of
silicon was added to molten crucible steel, which owing to the
presence of carbon and manganese evolved no important quan-
tity of gas. This steel contained 0.25 per cent, of carbon.
The result of adding the aluminium was to stiffen this steel,
make it hard to pour and difficult to get solid castings.
Mr. J. W. Spencer,* of the Newbern Steel Works, Newcastle-
on-Tyne, made a series of tests on this subject of the effect of
aluminium on crucible steel, and reached a similar conclusion.
With a low carbon steel, the effect on the tensile strength in-
creased with the increase of aluminium, but it was found on an-
alysis that the amount of silicon in the metal was also increased
by the treatment, which may partly account for the difference
in strength. The following table shows these results : —
Carbon
Aluminium
Silicon
in steel.
added.
present.
Elastic limit.
Tensile strength.
(per cent.)
(per cent.)
(per cent.)
(tons
. per sq. in.)
(tons per sq. in.)
O.IO
0.12
0.06
9.8
20.8
0-15
0.22
0.08
10.2
21.8
0.28
043
0.22
12.0
2S-S
These three steels were described as " fluid, sound and tough,"
excepting the last which was brittle before annealing. They
were all stronger before annealing. With high carbon steels
most of these properties were reversed, as is seen by the follow-
ing results :
Carbon
Aluminium
Silicon
in steel.
added.
present.
Elastic limit.
Tensile strength.
(per cent.)
(per cent.)
(per cent.)
(tons per sq. in.)
(tons per sq. in.)
0.53
0.12
0.28
14.38
29.60
0.65
0.22
0.28
14.38
26.28
0.8s
0-43
0.40
15.80
21.87
In these cases, as in the previous ones, the increase in carbon
and particularly silicon would cause a corresponding increase in
* Iron Age, Dec. 22, 1887.
ALUMINIUM-IRON ALLOYS. S8l
tensile strength; but it is very noticeable that with' carbon over
0.5 per cent, the strength decreases with the increase of alumin-
ium, in spite of a simultaneous increase in both carbon and sili-
con. These steels are also described as fluid and running into
sound castings, but they are brittle and hard before annealing,
particularly the one containing most aluminium. Mr. Spencer
sums up his experience as follows : " The result is satisfactory
in every instance so far as soundness and the usual attributes of
good castings are concerned, running fluid and without ebulli-
tion into sharp, clear castings ; the milder mixtures, under the
hammer, breaking very strong, though unannealed. The gen-
eral conclusion from the mechanical tests is that though alu-
minium may increase the elastic limit and tensile strength
slightly, yet this is done at the expense of ductility, while in
presence of high carbon it is disadvantageous in all these re-
spects. It is also probable that the increase of elastic limit and
tensile strength, when it does occur, is not more than can be
accounted for by the carbon and silicon present. The chemi-
cal reactions of the aluminium in the crucible may be various,
but the prevention of blow-holes and increased fluidity are
the chief advantages."
In order to avoid introducing impurities into steel by using
ferro-aluminium made from ordinary pig-iron, a German firm
put on the market a steel-aluminium " containing lo per
cent, of aluminium and 90 per cent, of pure cast-steel."
This can of course be used instead of ferro-aluminium for any
purpose, but it is particularly preferable in treating steel, which
is so extremely sensitive to minute quantities of certain impuri-
ties— sulphur, phosphorus, etc.
The rationale of the action of aluminium in preventing blow-
holes and increasing the fluidity of the metal will be discussed
more at length in considering the action of aluminium in the
mitis process, a little further on.
Effect of Aluminium on Wrought-Iron.
When wrought-iron is heated to a high temperature, it does
582 ALUMINIUM.
not pass quickly into the fluid state, but for a large increase of
temperature above the point at which it first softens it will re-
main thick or mushy. At a very high temperature it can be
made sufficiently fluid to pour into moulds, but the castings
thus made are notably unsound and weak. It was discovered
by Mr. Wittenstroem, of Stockholm, working with the co-ope-
ration of Mr. L. Nobel, of St. Petersburg, that if a small amount
of aluminium is added to a charge of wrought-iron which has
been heated until pasty, the iron immediately liquefies and
can be poured into castings having all the properties of
wrought-iron except fibre, and as sound as if of cast-iron.
This idea was investigated thoroughly at Nordenfelt's mallea-
ble-iron foundry, in Carlsvick, Sweden, by Messrs. Witten-
stroem, Nordenfelt, Faustman and Ostberg. The result of two
years' experimenting during 1883 and 1884 was so successful
that the malleable-iron plant was pulled down and a new
foundry, operated by Faustman and Ostberg, supplied their
former trade with wrought-iron castings, which were called
"Mitis" castings by Mr. Nordenfelt, because of their softness in
contrast with cast-iron castings. This plant began operations
in January, 1885, and its product soon reached a larger sale
than that of the malleable castings which it had supplanted.
Mr. Ludwig Nobel also installed the process in his foundry at
St. Petersburg at about the same time. The process was rep-
resented by a fine display at the International Inventions Exhi-
bition in London, in 1885, and received a gold medal. In
1885, Mr. Ostberg visited the United States for the purpose of
establishing the process here,* and a plant was erected and put
in operation at Worcester, Mass. In February, 1886, Mr. Ost-
berg spoke before the Institute of Mining Engineers at their
Pittsburg meeting, showing specimens of the castings ; an ex-
perienced iron worker said on that occasion that he would not
have believed the statements if they had not been proved by
the sight of the castings. In the same month, the "United
* U. S. Patent, 333.373; Dec. 29, 1885.
ALUMINIUM-IRON ALLOYS. 583
States Mitis Company" was incorporated in New Jersey, W. F.
Durfee, M. E., of New York, being general manager, Mr. Robt.
H. Sayre, of Bethlehem, Pa., president, and the list of directors
including Mr. John Fritz, manager of the Bethlehem Iron
Works, and several other well-kaown gentlemen. The object
of this company, which owns the " Mitis " patents for the
United States, is to regulate the use and sell rights to work
under these patents ; and it is said that five plants are now in
operation in the United States. Abroad, plants are working in
England, France, Germany, Austria, Sweden and Russia, The
experimental plant started at Worcester, Mass., has been aban-
doned for some time, it being said that the success achieved
there was anything but briUiant ; but since the process does suc-
ceed in other places, the plant in question was probably closed
for reasons satisfactory to those concerned..
Such, in brief, has been the rise of the mitis process. It
seems to have found its sphere in replacing malleable iron cast-
ings, because principally of the superior toughness of mitis
metal, although the castings are not so uniformly sound and
trustworthy, nor hardly so cheap, as those of malleable iron.
The following details of the production of mitis castings are
from descriptions by Nordenfelt, Ostberg, and E. A. Cowper,
of London : —
Raw material. — As the raw material to operate on, wrought-
iron scrap or mild steel are equally suitable. It was found that
some of the best results are to be obtained by using Swedish
scrap-iron or English hematite-iron — that is, materials contain-
ing less than o.i per cent of phosphorus, which is a very injuri-
ous ingredient if present in much larger quantity. Using a
mixture with poorer quality iron, with phosphorus running up
to 0.15 per cent., good results may still be obtained, that is, the
castings still compare favorably with ordinary malleable castings.
In using scrap steel, which is necessarily low in phosphorus, it
was found that manganese interfered with the production of
good castings, a result rather unexpected. Since almost every
melter devises various mixtures of his own, as circumstances
584 ALUMINIUM.
permit, it is but natural that we find the best features of the
mitis process united with some other old-estabUshed practices.
Thus, in one mitis plant in this country the mixture for melt-
ing was composed of:
Mitis scrap 35 per cent.
Hematite muck bar 35 "
Wrought iron punchings 12% "
Soft steel scrap (o.i per cent, carbon) 12% "
White pig-iron 3 "
Ferro-silicon (10 per cent, silicon) i "
ferro -aluminium (6 per cent, aluminium) ; % "
It is seen that in this charge the melter used a little white iron
as a flux, which would probably introduce O.i per cent, of car-
bon ; then the virtues of ferro-silicon for making sounder cast-
ings are utilized by adding o.i percent, of silicon to the charge;
lastly, 0.04 per cent, of aluminium was introduced.
In general, it may be said that if iron free from impurities is
used, very good castings are obtained ; if iron is used with a large
percentage of phosphorus, proportionately brittle and unsatis-
factory castings result.
The ferro-aluminium used should be, for similar reasons, fi^ee
from any considerable amount of such impurities as generally
injure wrought-iron.
Since the castings are almost identical in composition with
the charge of iron melted, the following analyses of mitis metal,
made by Mr. Edward Riley, will show the range of material or
mixture to which the process has been successively applied: —
Raw material. Carbon.
Hematite bar 0.067
Swedish scrap 0'053
Refined iron 0.130
'I ... 0.130
J^ Swedish scrap
%( Staffordshire iron I
^^ > ••■ 0.070 0.093
Silicon,
O.161
Phosphorus^
0.068
Manganese.
0.022
0.044
0.124
0.077
0-I37
0.027
0.014
0.035
0.150
0.026
0.194 0.014
j^ Hematite bar
Stafiordshire iron 0.106 0.080 0.250 0.014
The above figures are percentages ; sulphur was present in all
ALUMINIUM-IRON ALLOYS. 585
as a trace. The first in the table, those low in phosphorus,
gave the best castings, the last the poorest ; with over ^ per
cent, of phosphorus, the castings were brittle. As already
stated in considering steel castings, mixtures containing higher
percentages of carbon had been treated, but there seems to be
a limit to the increase of this element, above which the addition
of aluminium is no longer helpful, but even deleterious.
Method of treatment. — The charge of wrought-iron is placed
in covered crucibles and brought to a temperature of about
2200° (Mr. Ostberg), at which heat it is just losing the solid
and assuming the pasty condition. If it were desired to cast
the iron without adding aluminium, it would be necessary to
superheat it several hundred degrees above this point, not only
to give it the desired fluidity, but also to permit it being carried
around the casting shop. It is during this superheating that a
large part of the. gases contained in the molten iron are ab-
sorbed. If, therefore, the charge is treated with aluminium
immediately on reaching the melting point, the efTect is such
that this superheating with its accompanying deterioration of
the iron is rendered unnecessary. This is possible for the
reason that on adding ferro-aluminium sufficient to introduce
0.05 to o. I per cent, of aluminium, the charge immediately li-
quefies, and is so far from its setting point that it can be re-
moved from the furnace and poured into numerous moulds, re-
taining all the time its exceptional fluidity. The metal acts
just as if it had been superheated several hundred degrees, but
this has been accomplished without leaving it in the furnace
for half an hour or so, thus attaining an economy in fuel which
is not to be ignored. When the crucible is taken from the fur-
nace the charge is perfectly dead melted, lies quiet in the cruci-
ble, exolves no gas and teems like molten silver. It is cast in
either sand or iron moulds, and on account of its fluidity does
not require large heads to bring the castings up sharp and
show the finest impressions of the mould.
Several devices are used in connection with this process
which it may be interesting to note. The furnace used is one
586 ALUMINIUM.
designed and patened by Mr. Noble, and burns naphtha or crude
petroleum or petroleum residues. A full description with draw-
ings may be seen in Engineering and Mining Journal, May 8,
1886. With this furnace are melted on an average 8 heats in
10 hours. Starting cold, the first charges are melted in i^
hours ; when the furnace is fully up to heat only ^ hour is nec-
essary, so that the furnace is equal to 24 heats in 24 hours.
Any one familiar with steel melting will recognize this as a
great improvement in melting furnaces. The difficulty met
with in this country has been to get oil of uniform quality. At
the Chester Steel Casting Works they state that with one
car of oil the furnace works splendidly, but with the next they
may have difficulty in keeping up the heat. A supply of oil
of uniformly good quality is necessary for the successful work-
ing of this furnace. A patent pouring ladle is also used in
which the metal is kept up to its original heat as long as is
needed in order that a number of castings can be all poured at
the same temperature. The moulding material used is pure
fire-clay, hard burnt, finely ground and mixed with sugar or
molasses as a binding material. This is perfectly fire-proof at
the temperature of the molten wrought-iron, and is said to
answer well.
Properties of mitis castings. — The material being practically
wrought-iron, the castings do not have to be annealed before
using. The thinnest or most complicated castings can be pro-
duced, which it would be almost impossible to forge in wrought-
iron, thus furnishing difficult forged pieces at not much greater
expense than ordinary castings. When there is less than J^
per cent, of phosphorus present, the castings can be welded
and forged in all respects as wrought-iron. The castings come
out of the above moulding material with a remarkably smooth
surface and a peculiar bluish tint ; there is no sand burnt into
their surface. The castings are as ductile as the iron from
which they are made, but when tested for elongation under
stress it was found that they did not elongate so much. This
is counterbalanced, however, by the fact that as mitis metal
ALUMINIUM-IRON ALLOYS. 58/
contains no intermingled slag and absolutely no fibre, it has the
same strength and elongation in all directions. In general, the
tensile strength of the iron is increased, Mr. Ostberg says 20 to
50 per cent., but the lower figure is probably nearer correct.
Experiments at the Bethlehem Iron Works showed 10 per cent,
increase in tensile strength, with no change in the elongation.
Mitis castings are, in short, objects cast in low-carbon iron, yet
having all the desirable properties of wrought-iron. The uses
to which they can be put are very numerous, including all pur-
poses for which malleable castings are suitable, and particularly
to replace complicated or even impossible forgings in any
shape which admits of casting.
Rationale of the process. — The following facts are to be ex-
plained: I. On adding ferro-aluminium to wrought-iron
brought into a pasty fusion, the charge immediately becomes
very liquid. 2. The castings made of metal thus treated are
almost entirely free from the blow-holes which render ordinary
wrought-iron castings almost useless.
Mr. Ostberg's explanation of the first point is that the addi-
tion of the aluminium produces a sudden lowering of the fusing
point of the wrought-iron by some 150° to 250°, thus leaving
the metal superheated to that extent above its new melting
point, and consequently with greatly increased fluidity. That
this view is erroneous has been shown by the fact that the alu-
minium added does not remain in the iron. Numerous analy-
ses made abroad have failed to find any aluminium in the cast-
ings. Mr. R. W. Davenport, a trustworthy analyst, could find
it in no instance. Mr. A. A. Blair, of Philadelphia, one of the
greatest authorities on the analysis of iron and steel, has been
unable to find any, and considers it very improbable that 0.03
per cent, could escape detection. Mr. Ostberg also admits
that it has never been detected, and virtually abandons his ex-
planation by saying, in a letter to Mr. Howe, " An iron may
contain i or 2 per cent, of aluminium without any noticeable
effect in the making of castings ; it is not the presence of the
aluminium, but the act of adding it at a certain moment, that
produces the effect."
588 ALUMINIUM.
Mr. Osmond has definitely settled this question of the melting
point of aluminium-iron alloys by determining the fusing point
of an alloy with 5 per cent, of aluminium. This he found to
be only 25° below that of the pure iron, so that the efifect on
the melting point is really inappreciable.
Mr. R. W. Davenport offers the following explanation : A
rise of the temperature of the metal would explain the phenom-
ena as satisfactorily as a fall in the melting point. Since the
aluminium oxidizes and passes into the slag, probably accord-
ing to the reaction,
2AI + 6FeO = sFeO.AljO, + sFe,
the high calorific power of the aluminium would supply a con-
siderable quantity of heat, in spite of its small amount. Mr.
Davenport then assumes the calorific power of aluminium as
10,000, leaves out of consideration the heat absorbed by the
reduction of FeO to Fe and the union of FeO with Al^Oj to
form the aluminate, and from this calculates that the oxidation
of 0.06 per cent, of aluminium would produce 640 calories of
heat and raise the temperature of the bath about 40°. He fur-
ther implies that a rise of 120° would thus call for the oxida-
tion of only 0.18 per cent, of aluminium, which might easily
have been added to Mr. Ostberg's castings.
This explanation is as untenable as Mr. Ostberg's, for the
following reasons: i. The calorific power of aluminium burn-
ing to alumina is very nearly 7500* ; when producing hydrated
alumina (the datum usually given in the tables) it is only lop
higher. 2. The heat required to reduce ferrous oxide is pretty
accurately known, and there is no reason why this should not
be taken into account. 3. The heat of combination of ferrous
oxide and alumina is certainly not known, though probably
qiiite small; but on inspecting slag from mitis metal, white
patches or flakes of alumina are to be seen in it, showing that
some of the aluminium, if not the greater part, escapes as
* Ann, de Chim. et de Phys., June, 1889, p. 250.
ALUMINIUM-IRON ALLOYS. 589
alumina uncombined. It would be erring on the safe side to
leave this quantity out of consideration altogether. 4. As the
ferro-aluminium is thrown into the crucible cold, the melting of
it will very nearly absorb as much heat as is developed by its
chemical reactions. .Reconstructing the formula with these
points in view we have —
Heat developed. Heat absorbed.
Oxidation of aluminium
0.06X7250 =435
Redaction of ferrous oxide
0.24XJX1286 = 240
Melting of ferro-aluminium
1 .00 X 200 (Gruner) = 200
435 440
Making all reasonable allowances, the increase of heat due
to the addition of the alloy will be too small to be noticeable.
I might say, finally, that if the charge were left in the crucible
untreated, and heated one or two hundred degrees hotter than
the temperature at which the charges usually receive, their
ferro-aluminium, the wrought-iron would not flow with any-
thing like the fluidity shown by mitis metal. It is probably
safe to say that wrought-iron untreated could not, at any prac-
ticable temperature, be made as fluid as the aluminium-treated
metal.
What then will explain the increased fluidity? The author
asks a consideration of the following facts : Every metal melter
who has tried to run down wrought scraps of any metal, zinc,
copper, tin, etc., knows how the melt will become pasty, and in
many cases resist every effort to run it together. Now zinc is
zinc, and its melting point is somewhere about 420°, and yet the
surface of the scrap metal will keep together while the interior
is quite fluid. This is particularly noticeable with copper. It
appears that the previous working has driven particles of for-
eign matter, particularly oxide, into the pores of the metal, and
this less fusible skin keeps the melted particles from coming in
contact and running together. Again, it is noticeable with many
metals that the absorption or solution of a minute quantity of
590 ALUMINIUM.
its oxide tends to make the metal pasty. Let any one blow air
for a very short time through perfectly fluid zinc, and in an in-
credibly short space the metal will thicken up, and an amount of
mush out of all proportion to the amount of oxide which could
have been formed, will float on the surface. It can also be
noticed that on heating up this mushy metal again it passes out
of the solid state at nearly the same temperature as pure zinc ;
but instead of becoming fluid it remains pasty for many
degrees' rise of temperature above that point. The case of
wrought-iron appears to me to be similar to those just noted.
When wrought-iron scrap is heated it becomes soft at a mod-
erately high temperature, but on heating it further to get it to
form a homogeneous bath the hard, wrought surface is a great
hinderance to its running together; a very high temperature
causes the separate pieces to unite imperfectly into one body,
but because of the scale and oxide present from the first, to-
gether with that formed during heating, the fusion is thick and
viscid. Here the second phenomenon pointed out above can
be noticed. This metal, because of the oxide in it, requires a
higher temperature to make it fluid than if the oxide were not
there. What follows then ? Remove the oxide by some means,
and the bath becomes perfectly fluid, and is superheated with
respect to \i?, proper melting point, i. e., the melting point of the
metal uncohtaminated with oxide. The aluminium added does
this work, reduces the oxide to metallic iron, the infusible and
unalterable alumina produced rises to the surface, and the bath
attains its extraordinary fluidity for the reason just given.
With regard to the lessening of blow-holes, we will first note
their cause. First, they are not shrinkage cavities, which are
caused by the metal chilling too quickly after pouring in the
mould, and the sink-head not remaining fluid long enough to
feed the cavities made in the body of the casting as it cools.
The metal which is most liquid and least likely to chill quickly
will produce the least number of unfilled shrinkage cavities, and
these advantages are possessed by the wrought-iron when con-
verted into mitis metal. But, in considering blow-holes proper,
ALUMINIUM-IRON ALLOYS. 59 1
we note three distinct causes for them in wrought-iron cast-
ings.
1. When molten metal is poured into a mould prepared with
the greatest care there is always some ebullition caused by the
expulsion of moisture from the mould or moulding material.
This boiling will continue as long as the metal is fluid enough
to allow the vapor to escape, but as soon as it stops escaping,
there will be some gas entangled in the solidifying metal, pro-
ducing cavities. The gas thus entrapped is principally hydro-
gen with some oxygen, most of the oxygen being caught by
the metal and forming a lining of oxide inside the cavity.
2. When a stream of liquid, molten metal or water, is poured,
it draws with it into the bath a considerable quantity of air.
Every one who has poured water from a pitcher into a goblet
has had opportunity to see this phenomenon, which occurs just
as certainly and perhaps to a still greater degree when molten
metal falls six or eight inches through the air and down a pour-
ing gate. Such an arrangement is an actual suction apparatus.
The gas thus drawn into the metal will be principally air with
whatever proportion of moisture it contains. This gas escapes
as long as the metal remains fluid enough, but will be largely
entangled in the solidifying metal.
3. Metals possess the property of dissolving or occluding
gases while molten, just as water dissolves air. They can re-
tain some gas even when solid, but when they melt their dis-
solving power is largely increased. It results from this, that if
iron is kept molten for some time it will be able to dissolve a
certain quantity of gas. As it cools toward its setting point its
dissolving power may increase or decrease, I cannot say which ;
but it is certain that when very near to its setting point it sud-
denly loses this power of solution, and considerable quantities of
gas are evolved. The corresponding phenomenon in alumin-
ium is very marked and quite easy to observe (see p. 57).
The gas being set free near to the setting point, much of it is
entangled in the casting.
4. In castings made of cast-iron there is another cause of
592 ALUMINIUM.
blow-holes ; viz., the carbonic oxide produced by the carbon
present reducing oxides ; but since carbon is very low in mitis
castings and the dissolved oxides are otherwise removed,. this
cause need scarcely be taken into account.
Reviewing the causes of blow- holes, we note that the first two
will occur in casting any kind of metal, but that kind which is
most fluid in the mould and remains fluid the longest time will
permit most gases to escape and so set with the smallest num-
ber of blow-holes. The superiority of aluminium-treated metal
in these requirements gives it great advantages over these
causes of blow-holes. For the same reason, when the third
cause is considered, fluidity of mitis metal down almost to its
melting point, with a small range during which it is pasty, al-
lows more of the dissolved gas to escape when once set at lib-
erty. In the author's opinion, the increased fluidity of mitis
metal and the closer definition of its melting point, are the
chief causes of the comparative freedom of the castings from
blow-holes. However, the point has been raised by Mr. Howe,
that perhaps the aluminium imparts to the iron greater power
of holding gases in solution, not directly by alloying with it,
since none remains in the iron, but indirectly by removing the
oxygen. In one of Mr. Davenport's experiments, wrought-
iron was melted alone in a crucible, and while oxygenated and
boiling gently, i per cent, of ferro-aluminium was added, intro-
ducing 0.04 per cent, of aluminium and o.i per cent, of silico,)!.
It appeared to lessen the evolution of gas, and in 2J^ minutes
the iron was perfectly still, and when poured three minutes
later lay quiet in the mould like cast-iron. In all of Daven-
port's experiments with molten iron, the addition of aluminium
seemed to check the evolution of gas. We cannot say that
Mr. Howe's suggestion is impossible, yet it is very improbable,
because one of the laws of solution of gases in liquids is that
when a liquid has dissolved as much of one gas as it is able, it
will yet take up as much of another gas as if the first were not
present.* If then, we have the case of solution of gases in
*Deschanel's Natural Philosophy, pp. 182, 183.
ALUMINIUM-IRON ALLOYS. 593
molten iron, the removal of one gas would not affect the
amount of any other gas which the iron might take into solu-
tion. When wrought iron is boiling the cause is that carbon
present (perhaps that still left in the metal, but more probably
the graphite of the plumbago crucible) is reducing the dis-
solved ferrous oxide and forming carbonic oxide. To explain
the action of the aluminium in stopping this ebullition, it is not
necessary to suppose that it gives the iron increased power of
retaining in solution the gases which are escaping (Howe's ex-
planation), nor yet that it reduces the carbonic oxide gas as it
forms, which reaction might take place,* but simply that it re-
duces all the dissolved ferrous oxide at once, and so leaves no
available oxygen in the bath for the carbon to combine with.
With regard to any carbonic oxide which might be held dis-
solved in the iron, and by being evolved near the setting
point form blow-holes, it is quite probable that the aluminium
takes the oxygen away from it also, and so lessens chances of
blow-holes from this cause. If such gases as hydrogen or
nitrogen are dissolved in the molten' iron, the greater fluidity of
the bath will have no tendency to cause their evolution, the
aluminium cannot influence them chemically, and it is alto-
gether probable that they remain.
Professor LeVerrier has given a very satisfactory explanation
t)f the fact that the hydrogen and nitrogen also cease to be
evolved when the carbonic oxide stops being evolved. He cites
the case of carbonated water, saturated with gas, which evolves
nothing when quiet, but the agitation caused by blowing a very
gentle current of air through it liberates large quantities of gas.
Just so in steel. When the evolution of carbonic acid ceases,
the bath is no longer kept agitated, and in consequence the
other gases cease coming off also, producing a result appar-
ently out of all proportion to the quantity of aluminium which
produces it.
* Professor Arnold blew 40 gallons of pure carbonic oxide through a crucible of mol-
ten steel containing aluminium, and obtained an increase of 35 per cent, in the carbon
present in the metal, proving that aluminium can take oxygen away from carbon.
38
594 ALUMINIUM.
The arguments just presented may be summed up as follows :
1. Treatment with aluminium makes the bath fluid because
it removes the dissolved oxide which made it pasty.
2. Treating with aluminium stops the evolution of gas be-
cause— (a) It combines with all the oxygen present, and so
removes the essential gaseous ingredient of the carbonic oxide
which was being evolved ; (^) the stopping of the formation
of carbonic oxide allows the bath to remain quiet, and so the
other gases are not agitated out of the solution.
3. Treating with aluminium also lessens blow-holes in cast-
ings, because the greater fluidity of the metal allows the easier
escape of the gases mechanically entangled in it during cast-
ing.
Influence of Aluminium in Puddling Iron.
The Cowles Company state in one of their pamphlets that if
a small percentage of aluminium is added to iron in the pud-
dUng furnace, the bath comes to nature quicker, and the
wrought-iron produced is much stronger, equalling the best
grades of mild steel.
An article in the "Iron Trade Review," September, 1887,
stated that on adding o.i per cent, of aluminium to iron about
to be puddled, the tensile strength was raised from 52,000 to
60,000 lbs. per square inch, an increase of 16 per cent., while
the elongation was variously increased up to 20 per cent.
The only thoroughly reliable report on this subject is made
by Mr. G. W. Thomson, a gentleman connected with the well-
known firm, Messrs. P. & W. MacLellan, Glasgow. He took a
charge of 373 lbs. of No. 4 forge pig-iron, charged it into the
usual type of puddling-furnace, and when nearly melted threw
in an ingot of ferro-aluminium, which weighed 13 lbs., con-
tained 7. 11 percent, of aluminium, and so introduced 0.25 per
cent, of aluminium into the bath. The operation of puddling
then went on as usual, and with no noticeable change, except
that when the charge was just getting pasty it suddenly swelled
up considerably, slag flowed from it abundantly, and the charge
ALUMINIUM-IRON ALLOYS. 595
was very soon ready for balling. In the shingler and rolls the
balls worked decidedly stiffer than usual. The result was very
satisfactory. The ordinary iron averaged 22 tons tensile
strength, with 12 per cent, elongation. , The aluminium-treated
iron showed 31 tons tensile strength and 22 per cent, elonga-
tion, being gains of 40 and 80 per cent, respectively. These
bars stood the bending test perfectly, and when polished and
cut showed a remarkably fine surface and close grain. They
also forged satisfactorily.
If the above reports are to be relied on, this subject deserves
looking into by every puddling-mill manager desirous of im-
proving the quality of his iron.
Influence of Aluminium on Cast-Iron.
Very early in the history of aluminium, away back in 1858,
the Tissier Bros, suggested the possibility of this application of
aluminium by saying : " When aluminium has become low in
price, it will be interesting to see what qualities it can conr.-
municate to cast-iron, introduced in large or small quantities."
This suggestion does not appear to have led to any experi-
ments in this line until after 1885, when the discovery and
publication of the mitis process turned many experimenters
toward the determination of the effect of aluminium on cast-
iron. In April, 1886, Mr. Sellers, of Philadelphia, remarked at
the Washington meeting of the National Academy of Science
that he had made a series of experiments on the use of alumin-
ium with iron in casting, with the result that the castings pro -
duced were very sharp and without any flaws. In December,
1887, the Williams Aluminium Company, of Boston, began the
sale of an alloy called by them aluminium-ferro-sihcon, which
they recommended to founders for addition to cast-iron in the
ladle, claiming increased •fluidity of the iron and greater free-
dom from blow-holes. This company is now located in New
York, with works in Newark, N. J., and manufactures and sells
this alloy in tolerably large quantities. The claims of this
company, as also of other companies selling ferro-aluminium
596 ALUMINIUM.
for foundry practice, are certainly very broad, but we will dis-
cuss in how far they are probably true. These claims are, in
general, that the addition of aluminium —
1st. Makes the iron more fluid.
2nd. Makes hard iron softer.
3rd. Frees castings from hard spots and blow-holes.
4th. Lessens the tendency of the metal to chill.
Sth. Increases the resistance of the iron to chemical action.
It is also stated that while good, soft iron is made more fluid
and benefited to some degree, yet the advantages of treating
with aluminium are most evident with poor, hard, white iron.
We will review these claims in the Hght of those trustworthy
experiments which have been made and certified to.
It is now generally conceded that the addition of ferro-alu-
minium does affect the quality of the castings. The method
of adding it which has been generally adopted is to put some
pieces of broken ferro-aluminium into the bottom of a ladle,
preferably a hot one, and tap the iron from the cupola directly
on to the alloy. In this way the maximum benefit is obtained.
A German experimenter states* that it is important that the
iron be not too hot when the ferro-aluminium is added, for if it
is white-hot, the aluminium burns with a greenish flame and a
peculiar smell ; a golden-yellow heat is recommended as the right
heat for treatment. If the ferro-aluminium is thrown into the
molten iron at this heat, the streaks playing on the surface of
the metal disappear, and the bath becomes blistery looking.
The same writer states that, in general, white iron is undoubt-
edly improved by this treatment, but that gray iron is made
porous, the pores showing particularly in the lower parts of
castings.
While there have been many testimonials from practical men
as to the benefits derived from the use of ferro-aluminium, testi-
monies so numerous that the fact of benefit has become indispu-
table, the only systematic investigation of this subject is that
* Zeitschrift des Vereins Deutscher Ingenieure, 1889, p. 301.
ALUMINIUM-IRON ALLOYS. 597
made by Mr. W. J. Keep, of the Michigan Stove Company,
Detroit, with the co-operation of Prof. C. F. Maybery and L. D.
Vorce. Their results are embodied in two quite lengthy papers,
one read before the American Association for the Advance-
ment of Science at their Cleveland meeting, August 17, 1888,
the other published in the transactions of the American Insti-
tute of Mining Engineers, December, 1889. As we shall quote
many of the results given in these papers, we will first explain
the methods employed in pursuing the investigation.
Two kinds of iron were used, having the following composi-
tion : —
, White iron. Gray iron.
Silicon o.i86 1.249
Phosphorus 0.263 O.084
Sulphur 0.031 0.040
Manganese 0.092 0.187
Graphitic carbon 0.95 3.22
Combined " 2.03 0.33
Total " 2.980 3'S50
The ferro-aluminium used contained 11.42 per cent, of alu-
minium and 3.86 per cent of silicon. The melting was done in
a covered plumbago crucible, and the melt was run into test-
bars one foot long, some having a section y^ inch square,
others i inch wide and ^V inch thick. The ferro-aluminium
was added to the molten iron, the smallest quantity first, and,
after casting, part of this first cast was remelted with more
ferro-aluminium, and so on. Another series of heats was made
under exactly the same conditions but without adding alumin-
ium, these tests serving for comparison and determination of
the true effect of adding the ferro-aluminium. The general
plan of the tests consisted in adding 0.25, 0.50, 0.75, and i.oo
per cent, of aluminium to the white iron and 0.25, 0.50, 0.75, i,
2, 3, and 4 per cent, to the gray iron, the test-bars being care-
fully examined as to strength, shrinkage, etc., and comparison
made with the corresponding remelt of the iron alone.
The weak point of the first set of, tests, recorded in the first
598 ALUMINIUM.
paper, was the fact that many of the changes credited to the
addition of the ferro-aluminium might probably have been ac-
counted for by the silicon in the alloy added, and so the results
could not be accepted as demonstrating the influence of the
aluminium except where the change was in a direction con-
trary to that which the silicon could have produced. Mr. Keep
recognized at once the necessity of differentiating the effect of
these two elements, which was accomplished very ingeniously
by finding an iron containing the same amounts of silicon, car-
bon, etc., as the ferro-aluminium, and making comparison tests
with this iron in place of the aluminium alloy; also, by adding
pure metallic aluminium to the iron. Taking the second paper
in connection with the first, the conclusions advanced may be
regarded as final and beyond reasonable doubt. Since Mr.
Keep's method of presenting his results is in some cases not
easily understood, I have, from an inspection of his diagrams,
re-cast the results into tabular shape.
Solidity of castings. — All Mr. Keep's tests bore on this point,
but one particular test was made with white iron, adding only
O.I per cent, of aluminium (0.03 of silicon). The castings
were of slightly finer grain, but blow-holes and interstitial cav-
_ities were noticeably absent, this accounting for the largely in-
creased strength. The resistance to dead weight was increased
44 per cent., and to impact 6 per cent. No check test was
made to eliminate the effect of the silicon added, but the effect
produced was much greater than can with any probability be
ascribed to the silicon alone.
Does the aluminium remain in the iron f — To determine
this question, enough ferro-aluminium was added to white iron
to introduce 0.25 percent, of aluminium (0.08 of silicon), and
the resulting metal was re-melted five times. Samples were
taken of each melt, and found to contain at first addition 0.23
per cent, of aluminium, and at the successive re- meltings 0.20,
0.18, 0.15, 0.13 and o.io per cent, respectively. On compari-
son with white iron remelted alone the same nuiftber of times,
the influence on the strength is also seen to endure through
the re-meltings ; for instance —
ALUMINIUM-IRON ALLOYS. 599
Increase in Strength (per cent).
No. of Per cent. , ^ »
re-melting. of aluminium. Dead wt. Impact,
0.23 35 109
1 0.20 118 235
2 0.18 115 165
3 015 '23 150
4 0-13 32 62
5 o.io 21 39
The analyses of Mr. Keep's other tests also answer the above
question affirmatively, since, as before explained, the percentage
of aluminium was increased gradually by adding ferro-alumin-
ium to a previous melting, giving the aluminium several chances
to escape if it tended to do so, before a large percentage was
reached, but the calculated amounts agreed with those actually
found as follows : —
Found on Analysis.
Percentage by calculation. White iron. Gray iron.
0.25 0.25 O.IO
0.50 0.54 0.14
0.7s 0.89 0.32
i.oo 1.28 0.75
2.00 1.50
3.00 2.23
4.00 3-84
There were, of course, unavoidable irregularities in the mak-
ing of the tests, but the general conclusion from the above an-
alyses is that all the aluminium remains in the white iron and
almost all in the gray, the reason of the slight loss in the latter
case not being apparent. On adding small amounts of alumin-
ium to wrought-iron, none remains in the metal ; the reason
for the contrary phenomenon in the case of cast-iron is that the
presence of carbon in large quantity prevents the presence of
iron oxide dissolved in the iron, and the aluminium remains
because there is no such oxidized compound present to slag
itofif.
Transverse strength. — The addition of aluminium as ferro-
aluminium had the general effect of strengthening the iron, the
600 ALUMINIUM.
white iron showing the greater improvement, and the resistance
to impact being increased more than the resistance to dead
weight. The following table gives the percentage increase in
strength in each case, the minus quantities in parentheses mean-
ing decreased strength : —
White Iron.
Gray Iron.
Percentage of
,
aluminium.
Dead wt.
Impact.
Dead wt.
Impact.
0.2S
32-S
82.8
-(12-5)
-(15-5)
0.50
128.0
291.0
-(8.9)
44.0
0-7S
1 13.6
240.0
S.8
23.0
1. 00
1 1 7.6
350.0
2.4
30.0
2.00
—(10.4)
29.0
3.00
4.6
II.O
4.C0
iS-8
130.0
Since, for every i per cent, of aluminium added, 0.34 of sili-
con was contained in the ferro-aluminium, the question very
naturally occurred, how much of this benefit was due to silicon.
Tests were therefore made on this point, proving the part
taken by the aluminium. The figures show the percentage in-
crease in strength, as in the former tables.
White Iron.
Addition. Dead wt. Impact.
I per cent, aluminium in ferro-aluminium 1 1 7.6 3S0'0
Cast-iron, introducing the same quantity of silicon. 126.8 94.6
I per cent, of aluminium as pure aluminium I4I-7 156.5
The conclusions to be drawn are, therefore, that while the
silicon in the ferro-aluminium is sufficient to explain the in-
creased resistance to a dead weight, yet the increase in resist-
ance to impact is clearly due in large part to the aluminium.
Elasticity. — The closing of the grain of the iron on treatment
with ferro-aluminium caused the iron to be less brittle, or more
elastic. The deflection of the dififerent specimens for a fixed
weight was measured, and the increase in deflection was found
to be (in percentages) —
ALUMINIUM-IRON ALLOYS. 6oi
Gray iron.
125
116
147
133
"33
194
193
Percentage of aluminium.
White iron.
0.25
31
0.50
89
0.7s
100
1. 00
153
2.00
3.00
4.00
To distinguish the effect due to the silicon added, tests made
with siHcon and aluminium alone showed increased deflections
as follows :
Addition. White-iron.
I per cent, of aluminium in ferro aluminium 153
Cast-iron containing an equal quantity of silicon 11
I per cent, of aliuninium as pure aluminium 100
It is thus proved that the increased elasticity is due to the
aluminium, caused, as Mr. Keep believes, by a very uniform
distribution of the graphitic carbon when aluminium is the ele-
ment precipitating it, a phenomenon to be examined further on.
Effect on the grain. — Mr. Keep found that the addition of
ferro-aluminium made the grain of the iron decidedly darker,
caused by the separation of more carbon as graphite. It is
well-known that silicon acts in the same direction, but Keep's
first impressions were that the separation of graphite took place
much nearer to the setting point of the iron than he had ever
observed to result from silicon acting alone. A check test,
adding cast-iron without aluminium, confirmed this impression ;
for instance.
White-iron.
Addition. (Description of fracture.)
White.
0.25 per cent, aluminium as ferro-aluminium A few gray specks..
0.50 " " " " Light gray.
0.75 " " " " Gray.
i.oo " '■ " " Dark gray. -
Cast-iron containing an equal quantity of silicon to
preceding White— a few gray specks.
1.00 per cent, aluminium as pure aluminium Dark gray.
The comparisons made show that aluminium is undoubtedly
602 ALUMINIUM.
active in changing combined into graphitic carbon ; from a com-
parison of the analyses of the above tests it appears that it is
even more powerful than silicon in accomplishing this result,
since 0.25 per cent, of aluminium (with 0.20 per cent, of sili-
con) seems to give a fracture identical with that produced by
0.62 per cent, of silicon alone.
Mr. Keep notices that the separation of the graphite seems
to take place instantaneously just as the iron is about to set,
and not before, the result of which is that there is very little
opportunity for any gathering together of the graphite into soft
spots in the casting, and also that no matter how quickly the
iron sets, the graphite will be mostly separated out, and thus
the iron chills less. This effect is very noticeable in gray-iron,
where the first addition of 0.25 per cent, aluminium as ferro-
aluminium decreased the depth of chill fully one-half and
slightly darkened the fracture ; subsequent additions of two,
three and four times as much reduced the chill to nearly noth-
ing ; while with 2 per cent, of aluminium added, the drop of the
graphite was so nearly instantaneous that no chill was visible.
Fluidity of the iron. — The general conclusion from Mr.
Keep's tests is that, with white-iron, small additions of alumin-
ium, such as would be used in ordinary foundry practice, in-
crease slightly the fluidity; one-half per cent, of aluminium
and over decreases the fluidity. Gray-iron is rendered decidedly
less fluid by any addition of aluminium. Mr. Keep notices* a
peculiarity of cast-iron containing aluminium which is similar
to that we have remarked in pure aluminium (p. 446) ; viz.,
that as the metal flows it seem to have a skin in front of it,
causing it to run with a very thick edge, and if two currents of
this iron come together in a mould, they are apt not to unite,
but to simply chill without union.
Shrinkage. — Mr. Keep measured carefully the shrinkage of
the different specimens of aluminized cast-iron. The general
conclusion was that aluminium reduces the shrinkage if enough
of it is added. The following table shows the reduction in the
shrinkage, in percentage of the original shrinkage, under the
different conditions —
ALUMINIUM-IRON ALLOYS. 603
Reduction of shrinkage (per cent.)
White-iron.
Gray-
IRON.
Percentage of
aluminium.
Square bar.
Thin bar.
Square bar.
Thin bar.
0.25
-(4)
-(4)
0
14
0.50
0
-(4)
-(3)
4
0.7s
16
-(4)
4
14
1.00
21
-(4J
9
16
2.00
—
—
19
16
3.00
—
—
34
16
4.00
—
—
28
26
It will be noticed that, particularly with the square bar, the
first two additions of aluminium have very little effect either
way, but that with subsequent additions the amount of shrink-
age is reduced 5 to 30 per cent. Mr. Keep thinks that this
behavior is dependent on the action of the carbon ; that the
small amounts of aluminium are chiefly active in closing blow-
holes and giving soundness to the casting, but the larger
amounts have a noticeable influence on changing combined
carbon into graphite, and that the increased deposition of
graphite just as the metal sets increases its volume and de-
creases the amount of shrinkage.
Hardness. — The indications from Mr. Keep's tests are that
aluminium of itself hardens cast-iron, but, by its influence in
changing combined' carbon into graphite, it indirectly renders
the iron softer. It is noticeable that if an iron cast with soft
spots, the parts in between being hard, that the addition of alu-
minium caused the graphite to be dropped so near to the set-
ting point that it had no opportunity to collect into spots, and
was therefore uniformly distributed, rendering the iron uni-
formly softer.
Aside from the above determinations, many testimonials
could be quoted from practical iron founders as to the practical
benefit to poor iron gained by adding ferro-aluminium. Per-
haps one of the most striking results is the increased time
which the aluminium-treated iron will remain molten. For in-
stance, Mr. Keep found that 0.02 per cent, of aluminium added
to a ladle of iron caused it to keep fluid 5 minutes, while a simi-
604 ALUMINIUM.
lar ladleful of the same metal without aluminium became solid
in 2j4 minutes. This property of keeping fluid longer is of
direct usefulness in a foundry where it is necessary to run a
large number of small castings, during which operation there is
usually much trouble experienced in keeping the iron fluid,
unless it was very hot to start with. I am quite assured of the
fact that the addition of a very small amount of aluminium does
have the efifect described above. A friend of the author
described an experiment in which a large ladleful of iron was
tapped from a cupola and taken for pouring about 200 yards,
partly through the open air. The iron was not hot enough to
fill the moulds satisfactorily. Another ladleful, similar in all
respects, was tapped immediately after, some ferro-aluminium
being placed in the ladle. This iron was taken to the same
place for casting, filled the moulds perfectly, and when brought
back to the cupola the metal left in the ladle was still fluid
enough to make good castings. I have heard similar reports
from trustworthy sources, all stating that the judicious use of a
small quantity of ferro-aluminium will result in nearly doubling
the time during which a bath of iron will stay fluid enough to
make castings.
The practical results observed by the foundrymen are that
they obtain cleaner, more solid, softer casti-ngs, with a large
reduction in the percentage of defective castings. Mr. Adam-
son, President of the British Iron and Steel Institute, says that
" since using ferro-aluminium in my foundry, 80 per cent, of the
the waste has been saved, and all the work manufactured is
improved in quality." The general testimony seems to be
that the castings come out of the sand cleaner, are much more
free from blow-holes, work more uniformly in the lathe or
planer because of the absence of hard or soft spots, come up
sharper in the mould, and are generally stronger. There is not
much improvement made on good gray foundry iron, in which
case it is best to leave the good iron to itself ; but when the
quality of the iron is low, and difficulty met in getting good cast-
ings, then ferro-aluminium is of undoubted benefit. Very small
ALUMINIUM-IRON ALLOYS. 60S
additions are relatively of greatest effect ; Mr. Keep has stated
that with only 0.00067 P^i" cent, of aluminium added to a poor
quality iron it could be observed that the blow-holes were les-
sened and the transverse strength noticeably increased. It is
probable that the first one-hundredth of a per cent, of alu-
minium added has more effect than the next five-hundredths ;
and it is fortunate that this is so, for it opens up an extremely
large field for the use of aluminium alloys.
The rationale of the action of aluminium on cast-iron may be
said to be an open question. That 0.25 to 0.50 per cent, begins
to affect the carbon has been proven by Mr. Keep, yet these
are quantities which are not used in ordinary foundry practice,
where o.io per cent, may be taken as the maximum amount
which the founder can afford to use, while o.oi to 0.05 percent,
may be said to be the usual additions. It would appear to me
that such small proportions of aluminium can only exert the
effects attributed to them by (expressing it figuratively) holding
a sort of balance of power, by which it determines a much greater
result than the aluminium alone could possibly bring about.
This idea is alluded to by Mr. Keep when he says that to use
ferro-aluminium to best advantage the cast-irons should be
mixed so as to get mixtures most suitable for treatment, or in
other words, to get an iron more sensitive to the aluminium.
What the conditions are which render an iron sensitive to the
action of the aluminium has not been definitely determined.
We might infer that since it acts in many respects similarly to
silicon, the less the amount of silicon present the larger the
scope of the aluminium, that is, the more room it has to act.
Or, similarly, the more combined and less graphitic carbon
present, the more opportunity is given the aluminium to bene-
iit the iron. But, why the aluminium-treated iron should stay
fluid so much longer, we cannot see. This seems to be one of
those effects out of proportion to the quantity of aluminium
present. For the present, we will rest the case here ; practi-
cally, very small additions of ferro-aluminium can be made very
advantageous; theoretically, we have, as yet, no satisfactory
explanation of the facts observed.
CHAPTER XVII.
ANALYSIS OF ALUMINIUM AND ALUMINIUM ALLOYS.
Commercial aluminium may contain the following elements
besides aluminium : Silicon, iron, lead, tin, zinc, copper, silver,
carbon, sodium, chlorine, fluorine. The method of attack gen-
erally preferred is solution in pure caustic soda. Hydro-
chloric acid usually attacks aluminium very energetically, and
more easily the larger the percentage of silicon it carries, for the
purest aluminium is not attacked very violently. When much
silicon is present, the odor of silicuretted hydrogen is plainly
perceptible during the action of the acid, thus indicating some
loss of silicon. In dissolving in caustic soda this loss does not
take place. Solution in bromine or iodine solution also offers
similar advantages as respects avoiding loss of silicon. When
analyzing particularly for carbon, the solvent used in the de-
termination of carbon in iron may be appropriately used. We
will consider these more in detail further on.
A qualitative test may very appropriately precede the analy-
sis, and will often save much time in the quantitative determi-
nations. These qualitative tests may generally be made on the
same lines as the others ; though in some cases shorter methods
are practicable. Thus, after solution in hydrochloric acid, neu-
tralizing with and adding excess of ammonia will show the
presence of copper. If the solution is made hot, a spot of sul-
phuric acid will show whether lead is present. Iron may be
detected by potassium ferro-cyanide. Silver will remain as a
white residue after the action of the acid. Chlorine is detected
most easily by Berzelius' blow-pipe test with oxide of copper.
Lead and zinc can be detected to a certain extent before the
blow-pipe. A specimen of aluminium which gave an unmis-
(606)
ANALYSIS OF ALUMINIUM. 607
takable test for lead on charcoal before the blow-pipe, was
found on subsequent analysis to contain nearly 7 per cent, of
that metal. It appeared as though a much smaller proportion
could have been thus detected. Another specimen similarly
treated gave a good test for zinc, and the quantitative analysis
gave 6.25 per cent, of that metal. Smaller amounts than this
could probably be easily detected. On the other hand, how-
ever, it is not probable that the presence of tin would make it-
self evident in the charcoal test; for aluminium seems to pro-
tect the tin very strongly from oxidation. An alloy known to
contain 90 parts of tin to 10 of aluminium was tested on char-
coal, and would not, with the hottest flame at my command,
give the usual white coat indicating tin. Such being the case,
it appears highly improbable that aluminium containing a small
percentage of tin would give the test in question. The better
test would be the white residue left on solution in hot, concen-
trated nitric acid. The presence of iron or copper, or of both
together, can usually be immediately recognized by dissolving
a small piece of the aluminium in a borax bead, on a platinum
wire, in the oxidizing flame. Copper thus detected by the au-
thor was found on analysis to be less than i per cent, of the
weight of the aluminium tested. The presence of sodium is
generally shown by the metal decomposing water heated nearly
to boiling, setting free hydrogen. This test can be easily made
in a test-tube.
The specific gravity of the metal, accurately taken, furnishes
some intimation as to the presence of any of the heavy metals
in any considerable quantity. Thus, 5 per cent, of silver in-
creased the specifiq gravity from 2.65 to 2.8 ; 6 per cent, of lead
from 2.7s to 2.9. This test is not, however, of much value,
since, because of the very low specific gravity of aluminium,
small amounts of heavy metals have only a small influence in
increasing it, while silicon, an impurity most likely to be pres-
ent, is lighter than aluminium (specific gravity 2.35), and
therefore neutralizes to some extent the effect of the heavy
metals. However, in commercially pure aluminium, containing
6o8 ALUMINIUM.
only iron and silicon, the specific gravity can be made useful in
indicating the amount of iron present within rather wide limits
— say within i per cent.
Another test of somewhat similar utility would be that given
by Fr. Schulze.* He proposes to dissolve the aluminium in
caustic alkali and measure the volume of hydrogen set free. If
the metal contains no zinc, this volume will be approximately
proportional to the amount of aluminium in the metal. Thus,
Yi gramme of one specimen gave 648 cubic centimeters of hy-
drogen; a similar weight of another, 580 cubic centimetres.
These figures are then taken as expressing the relative purity
of the two samples. In an aluminium works where a quick,
approximately accurate test is needed, which can be made, if
need be, by a person not necessarily a skilful chemist, and
which is applied to testing samples of nearly the same compo-
sition, this test would appear to be of practical utility.
Determination of silicon. — Deville recommended the follow-
ing method : " Dissolve in pure hydrochloric acid and evap-
orate to dryness in a platinum dish. The evaporation to dry-
ness is indispensable in order to render insoluble the quite
important quantity of silica which is kept in solution by the
presence of the acid. There remains an insoluble residue con-
sisting of silicon, silicon protoxide and silica, which is washed
by decantation with hot water and thrown on to a filter. This
mixture of siliceous material is then calcined with the filter*in
a platinum dish at low temperature. A little flame may often
be seen coming from dififerent parts of the mass, caused by the
production (at the expense of the silicon protoxide) of a little
silicon hydride, according to the reaction —
3SiO+2H20=SiH4+3SiO,
causing a slight loss of silicon. This may be altogether avoided
by moistening the material with ammonia before calcining.
The residue after ignition is a mixture of silicon and silica, the
* Wagner's Jahresbericht, x. 23.
ANALYSIS OF ALUMINIUM. 609
silicon protoxide having completely disappeared, and is care-
fully weighed. This done, it is put into a platinuni crucible,
and treated with a little dilute hydrofluoric acid, which dis-
solves the silica and leaves the silicon, which is washed with
care. This residue is then dried and weighed, and by subtract-
ing from the former weight, the weight of silica is known with
which it was mixed. This silica is calculated to silicon, and
when the silicon weighed directly is added in, the result is the
total weight of silicon in the metal tested."
The above method probably does determine with accuracy
the amount of silicon which remains after solution of the alu-
minium, but Rammelsberg observed (see p. 56) that when alu-
minium contains considerable silicon there is always some sili-
con hydride formed during its solution in hydrochloric acid,
which escapes and so causes error in the analyses. By passing
the gases produced during solution through a solution of caus-
tic potash, the silicon hydride was intercepted and the amount
of silicon thus escaping was determined. It was found to be in
two instances, 0.74 and 0.58 per cent., being 7 per cent, and 22
per cent respectively, of the total silicon in the metal (the first
was very siliceous). It follows, therefore, that to make an ac-
curate determination of the silicon in aluminium, hydrochloric
acid cannot be used for attacking the metal unless care is taken
to catch and determine the amount of silicon passing off as
silicon hydride. Prof. Rammelsberg concluded from his study
of the subject that silicon occurred in two forms in aluminium,
a small amount free (like graphite in iron) the larger amount
combined, and that on treatment with hydrochloric acid the
free silicon remained as such, while the combined silicon partly
escaped as silicon hydride and the rest was converted into
silica. Such being the case, we can readily see the superiority
of caustic potash or soda solution for dissolving the aluminium.
Graphitoidal or crystalline silicon is dissolved by hot potash so-
lution, the combined silicon will be dissolved, and if the nas-
cent hydrogen forms for an instant any silicon hydride — as it
does when acid is used — this gas is at once decomposed by the
39
6lO ALUMINIUM.
alkali solution. The result is that if aluminium is attacked by
hot potash solution, all the silicon present is oxidized and none
lost. The solution of the aluminium should take place in a sil-
ver or platinum dish or crucible ; a porcelain dish, however, is
very slightly attacked, but glass should not be used. Care
should be taken that the solution of caustic does not contain
alumina or silica. After solution is complete, the liquor is fil-
tered from any residue, hydrochloric acid is added until the re-
action is acid, the bath evaporated to complete dryness until no
smell of acid is perceptible, then moistened with a little hydro-
chloric acid to dissolve any alumina formed, water added and
the whole brought to boiling. The silica is then filtered out,
dried, ignited, weighed and calculated to silicon.
F. Regelsberger, chemist for the Aluminium Industrie Actien
Gesellschaft, at Neuhausen, Switzerland, recommended using
nitric acid to which was added one-fifth of its volume of hydro-
chloric acid. The oxidizing power of the nitric acid prevents
any loss of silicon as silicon hydride, and solution of the alu-
minium takes place completely when the acid is warmed. This
is the best and also the cheapest method of getting the alumin-
ium into solution, and determining the total silicon. Mr. J. O.
Handy, chemist of the Pittsburg Reduction Company, conducts
the analysis as follows : * One gramme of turnings or drillings
of the metal are dissolved in a mixture of 15 c.c. strong nitric
acid and 2 c.c. concentrated hydrochloric acid. When 'the
solution is nearly complete, add 2 c.c. more of the hydro-
chloric acid, and warm. When completely dissolved, add
20 c.c. of concentrated sulphuric acid, evaporate quickly on a
hot plate until fumes of sulphuric anhydride appear, cool, add
75 c.c. of water and 10 c.c. of hydrochloric acid, stir well, boil
for five minutes, and filter out the mixture of silicon and
silica. Wash first with water, then with hot, dilute (30 per
cent.) hydrochloric acid, and then with water, until free from
acid. The filtrate may be used for determining aluminium,
iron, etc. The silicon and silica are dried and fused with
* Journal of Applied and Analytical Chemistry, January, 1892.
ANALYSIS OF ALUMINIUM. 6ll
about 3 grammes of sodium carbonate. After fusion, dis-
solve in hot water with hydrochloric acid, add 1 5 c.c. of con-
centrated sulphuric acid, evaporate to sulphuric fumes, cool,
add 75 c.c. of water and 10 c.c. of hydrochloric acid, heat to
boiling and filter. Wash with water, 30 per cent, hydrochloric
acid, then with water, and weigh as silica. If it is desired to
determine the graphitoidal silicon, another sample is dissolved
in the same way, but the mixture of silicon and silica first ob-
tained is filtered out upon platinum sponge in a platinum filter
in a Grooch crucible, washed, dried at 80° C. and weighed.
Then wash with hydrofluoric acid and sulphuric acid, thus dis-
solving away the silica, wash with hot water, dry again at 80°
and weigh quickly the graphitoidal silicon. The loss in weight
is, of course, the silica representing the combined silicon in the
sample of, metal.
Determination of iron {and aluminium'). — Deville's method
of procedure was as follows : " The metal is dissolved in pure
hydrochloric acid, evaporated to complete dryness in a plati-
num dish, and the insoluble, siliceous materials filtered out.
The solution is mixed with a large excess of nitric acid, evap-
orated in a porcelain dish covered by a glass, thus converting
the bases into nitrates, which are then transferred to a platinum
dish. Here the solution is evaporated to dryness and calcined
lightly on the sand-bath, the dish being covered, until abund-
ant vapors of nitric acid rise from all parts of the mass. Cool,
and moisten with a solution of ammonium nitrate containing
free ammonia. Heat until all odor of ammonia has disap-
peared, take up with water, and separate by decantation all sol-
uble matter. (Decanting for greater precaution on to a filter.)
The solution obtained contains all the sodium which was in the
aluminium (see Determination of Sodium), while the insoluble
residue is a mixture of aluminium and ferric oxide. This is
heated to redness in the platinum dish which contains it, and
transferred in whole or part into a tared platinum boat, where
it is weighed. (It is best to make all these weighings with the
boat inclosed in a glass tube closed by the flame at one end,
6l2 ALUMINIUM.
and at the other by a well-fitting cork. The tube and boat are
then weighed together.) The boat is then placed inside a por-
celain or platinum tube, heated up to redness, and a current of
pure hydrogen passed over it. When the tube is bright-red,
the hydrogen is replaced by hydrochloric acid gas, which
transforms all the reduced iron into ferrous chloride without
touching the alumina. At the end of the operation, when the
tube is just below redness, the hydrochloric acid gas is replaced
by hydrogen. When nearly cold, the boat is drawn out and
weighed, the loss in weight bei«g the ferric oxide removed, the
portion still remaining being pure alumina. From these data
the iron and aluminium are calculated. Very little trust can be
placed on the alumina being perfectly white, to conclude that
it is, therefore, free from iron ; for experience has taught me
that one may be very greatly deceived in making this con-
clusion. Experience will show about how long and at what
heat the operation must be continued to remove all the iron ;
but to be absolutely certain, the operation should be repeated
for a short time, when the alumina will remain constant in
weight if it is perfectly pure."
The above operation is the most accurate method of deter-
mining iron and aluminium, and is more applicable to estimating
small quantities of iron in aluminium rather than vice versa,
since in the latter case the operation is much prolonged in re-
ducing and volatilizing the iron compounds. The estimation
of small amounts of aluminium in presence of a large quan-
tity of iron generally calls for special methods of separation,
which will be detailed under the analysis of aluminium-iron
alloys. Confining ourselves here to the determination of iron
in commercial aluminium, we may suggest the following modi-
fication of the above method. After solution in hydrochloric
acid and separation of silica, the addition of a few drops of sul-
phuric acid will precipitate any lead which may be present, and
then the iron and aluminium may be precipitated with
ammonia in slight excess. Any copper present will remain in
solution, and the precipitate may be washed well, filtered.
ANALYSIS OF ALUMINIUM. 613
ignited, and weighed. Instead then of removing the ferric
oxide by the method given by Deville, the method of H. Rose
may be used, which consists in fusing the two oxides with
caustic potash (by alcohol) or caustic soda (from sodium) in
a silver crucible, when alkaline aluminate will be formed, and
on boiling the mass with water and filtering, the alkaline fluid
will contain the aluminium, while the residue will be ferric
oxide containing some potash.
If a solution has been prepared containing only iron and alu-
minium (lead, zinc, copper, etc., having been separated out)
many methods have been proposed for separating these two
elements. The oldest method is to make the solution nearly
neutral and then pour it gradually into excess of pure caustic
potash or soda solution heated nearly to boiling in a platinum
or silver dish. The iron is precipitated, while aluminium re-
mains in solution. The details of this test can be found in any
treatise on quantitative analysis. It is not to be relied on in
many cases, especially for determining a small amount of alu-
minium in presence of much iron, since it is always prob-
able that some aluminium is retained by the iron precipitate.
Dissolving the iron hydroxide and reprecipitating will par-
tially correct this. Solution of ordinary caustic soda is more
apt than caustic potash to contain alumina, and so only the
caustic soda made from sodium should be used. In either case
the alkaline solution of potassium or sodium aluminate is
heated nearly to boiling, and mixed with a large excess of am-
monium chloride, when the alumina is entirely precipitated.
The method most frequently used to separate ferric oxide
from alumina is to weigh the two oxides together, then dissolve
in concentrated hydrochloric or sulphuric acid, reduce the solu-
tion by any suitable reducing agent (zinc, sulphurous acid gas,
etc.), and determine the amount of iron present by titration
with potassium permanganate or bichromate solution. These
results are quite accurate if the proportion of aluminium is not
small; when the latter is the case, as in ferro-aluminium, other
methods give more satisfactory results, and are given further on
in considering the analysis of ferro-aluminium.
6l4 ALUMINIUM.
The solution of the aluminium to be tested in caustic alkali
offers the quickest method of separating out the iron, for the
alkali dissolves out all the aluminium and leaves iron in the
residue. The best way to conduct this method of analysis is to
roll out the aluminium into a thin sheet, put in moderately con-
centrated alkali and allow it some time to dissolve. On filter-
ing, the solution will contain all the aluminium while all the iron
will remain, with various other metallic impurities, in the
residue. This residue is then dissolved in acid and the iron
easily determined in it without any interference from aluminium.
Determination of lead. — Dissolve the aluminium in hot hydro-
chloric acid, evaporate to dryness, moisten with hydrochloric
acid, add hot water, and boil. Filter hot to separate out silica.
To the hot, boiling solution add a few drops of sulphuric acid
and let stand an hour. The precipitated lead sulphate can
then be filtered out and weighed.
Determination of copper. — Proceed as in determining iron,
when the copper will pass into the filtrate on precipitating iron
and aluminium by excess of aqua ammonia. If any amount of
copper is present this solution will be blue, especially when con-
centrated by evaporation. The solution may be evaporated to
dryness, taken up with a little acid and the copper determined
by any ordinary method ; or, the ammoniacal copper solution
may be acidified with sulphuric acid, crystals of oxalic acid
added, the liquid boiled, and the copper thus deposited as
oxalate. This is washed in boiling water, dried, calcined at a
gentle heat, and weighed as cupric oxide. The ammoniacal
copper solution might also be acidified with acetic acid and the
copper precipitated by lead foil.
Determination of zinc. — Dissolve the aluminium in hydro-
chloric acid or in caustic alkali and separate out silica, taking
up, however, with strong acetic acid. On passing sulphuretted
hydrogen through the solution, zinc will be precipitated free
from aluminium or iron. The precipitate of zinc sulphide is
washed carefully with distilled water saturated with sulphuretted
hydrogen, dried, calcined very carefully in a muffle and after-
ANALYSIS OF ALUMINIUM. 01$
wards very strongly over a blast lamp, and weighed as zinc
oxide.
A very satisfactory separation is also obtained by nearly neu-
tralizing the solution, adding a limited quantity of acetic acid
and then sodium acetate, and thus precipitating the aluminium
(and iron) as basic acetates, leaving the zinc in solution, from
which it can be precipitated by a current of sulphuretted
hydrogen.
Determination of tin. — ^Solution of the aluminium in hot
nitric acid will leave the tin as insoluble meta-stannic acid.
This residue is washed and treated with warm, dilute hydro-
chloric acid, which dissolves the tin compound and leaves the
silica. The tin is then thrown down in the solution of stannic
chloride by any of the ordinary methods of precipitation, pre-
ferably by sulphuretted hydrogen. The stannic sulphide is
ignited gently, moistened with nitric acid, ignited more strongly,
and the tin weighed as stannic oxide.
Determination of silver. — Dissolve the aluminium in weak
aqua regia, dilute and filter out the siHceous residue, which will
contain also all the silver as chloride. Wash carefully, and
then dissolve out the silver salt with concentrated ammonia.
On neutralizing the ammoniacal solution with nitric acid, the
silver chloride is again precipitated, washed by decantation,
dried at 250° to 300°, and weighed.
If the aluminium is attacked with caustic alkali, the silver will
remain in the residue. This is washed, filtered, and treated
on the filter with dilute nitric acid, which dissolves the silver.
The solution of silver nitrate is precipitated by hydrochloric
acid or sodium chloride, and the operation finished as before.
Determination of sodium. — In the first steps of the deter-
mination of iron, as given by Deville (p. 611), a solution was
obtained free from iron and aluminium, and containing all the
sodium which was in the aluminium tested. Deville describes
the estimation of the sodium in this solution as follows : " To
the solution is added a drop of ammonium oxalate, which
sometimes precipitates a trace of calcium, indicative of the
6l6 ALUMINIUM.
presence of fluorspar in the slag with which the metal may be
impregnated. After filtering (if necessary) evaporate to dry-
ness in a weighed platinum dish, cover and heat to 200° or
300°, to decompose the ammonium nitrate. Nitrate of soda
remains. This is moistened with water, and on it are placed
several crystals of oxalic acid. Dry, calcine, and there re-
mains sodium carbonate, which is often impregnated with a little
carbon from the decomposition of the oxalate of soda. Dis-
solve the residue in water ; if not clear, filter. Mix the solu -
tion with a little hydrochloric acid, evaporate to dryness, heat
to 200°, and weigh as sodium chloride."
Commercial aluminium rarely contains metallic sodium, but
when it does exist it can usually be detected from the fact that
the amount of chlorine present is not sufficient to combine with
the sodium found. The presence of fluorine would weaken
this conclusion, but it is seldom present in any quantity.
Determination of chlorine. — Dissolve the aluminium in pure
caustic soda, neutralize with nitric acid in very small excess,
filter, and add several drops of nitrate of silver. The chloride
of silver precipitated is washed well, dried at 300°, and weighed.
Determination of carbon. — Carbon occurs probably all as com-
bined carbon. A large proportion of this carbon would neces-
sarily escape on treating the aluminium with acids or alkalies, for
the nascent hydrogen developed during solution would form
volatile hydrocarbons with it. To obviate this, the ammonkal
solution of copper chloride should be used as a solvent, as in
carbon determinations in iron. Solution in this, or, perhaps,
in bromine, give a means of estimating the total carbon present.
See Le Verrier's determinations on p. 57.
Detection of fluorine. — Deville recommends the following pro-
cedure : " Dissolve in caustic soda (using no more than is
necessary), filter, and nearly neutralize with pure sulphuric acid.
It is necessary to take care to leave a very small amount of free
alkali without separating out any alumina, which falls at the mo-
ment when neutralization is complete. Evaporate the whole in a
platinum crucible, and heat, covering with a watch-glass coated
ANALYSIS OF ALUMINIUM. 617
with varnish through which regular lines have been traced with
a copper point. A section of quartz prepared in the same way
does still better. Vapor of water and hydrofluoric acid are
disengaged on heating the crucible, and the latter . etches the
glass quite perceptibly. Sometimes, by breathing on the
glass, the lines become more apparent.
Determination of Titanium. — Dissolve 2 grammes of the alu-
minium in caustic alkali solution, bring to boiling and filter
quickly, washing repeatedly with boiling water. The residue
contains all the iron and titanium. Dry and fuse with 8
grammes of potassium acid sulphate. After complete fusion,
taking perhaps thirty minutes, dissolve in hot water and filter
out the silica. To the solution add dilute ammonia until a
sHght percipitate forms, add dilute sulphuric acid until the pre-
cipitate just rc'dissolves, then add 4 drops of concentrated sul-
phuric acid, dilute to 250 c. c, and saturate with sulphurous
acid gas. Heat slowly to boiling and boil gently for 45 min-
utes, occasionally adding a little strong sulphurous-acid water.
Filter out the precipitated titanic oxide, wash thoroughly with
hot water, dry, ignite and weigh as TiOj.
In the filtrate, the iron can be determined by oxidizing the
solution, precipitating with ammonia, washing, re-dissolving in
sulphuric acid and titrating with potassium permanganate.
(Handy.)
Determination of Chromium. — This element is only present
when intentionally introduced. The aluminium-chromium alloy
is treated as for detecting titanium, when the chromium will re-
main in the residue with titanium, iron and silicon. This resi-
due is put in a platinum crucible and treated with i c. c. of
concentrated sulphuric acid and 5 c. c. of hydrofluoric acid.
Evaporate to sulphuric fumes, then add 4 grammes of potas-
sium acid sulphate and fuse, finishing the fusion over the blast
lamp. Cool, add enough sodium carbonate to make the fusion
alkaline, ialso some nitre, and fuse again. Take up in hot water
and filter. Add some ammonium chloride, heat and filter out
any alumina. Reduce the solution by sodium hyposulphite or
6l8 ALUMINIUM.
sulphurous-acid gas, and precipitate the chromium by am
moiiia. Re-dissolve the precipitate in hydrochloric acid and
re-precipitate with ammonia, wash, dry, ignite and weigh as
Cr,0,. (Handy.)
Analysis of Ferro- Aluminiums.
It is not intended to give directions for the complete, analysis
of ferro-aluminium. The determinations of silicon, carbon,
sulphur, phosphorus, etc., are made the same as in steel or pig-
iron. The only point offering special difficulty is the accu-
rate determination of a small amount of alummium in presence
of a large amount of iron. For doing this, the ordinary
methods do not give satisfactory results. Thus, when deter-
mining the iron volumetrically and the aluminium by dififer-
ence, it is almost impossible to get concordant results When
separating by caustic alkali, the results in aluminium are too
low, for the iron precipitate being so abundant, carries much
aluminium down with it. Also, a large amount of caustic alkali
must be used, and since it sometimes contains alumina, con-
siderable error may thus be thus introduced.
Supposing that the alloy has been dissolved in acid, silica
separated out and a solution containing only iron and alumin-
ium obtained to work with, we will take up the various methods
proposed to determine accurately the small amount of aluminium.
Mr. H. N. Yates analyzed several hundred specimens of
ferro-aluminium, and found that the caustic alkali separation
gives aluminium too low, and is unreliable ; the method of
weighing the two oxides together and afterwards determining
the iron volumetrically with potassium bichromate gives pretty
fair results with aluminium from i to 19 per cent.; but, with
less than i per cent., as in steels, the most satisfactory results
were obtained by the sodium thiosulphate separation. This
latter is known as Chancel's separation, and is operated as fol-
lows : The solution is neutralized with sodium carbonate, made
dilute, solution of sodium thiosulphate (hyposulphite) added,
and the liquid boiled until no moce sulphurous acid is disen-
ANALYSIS OF ALUMINIUM. 619
gaged. All the alumina is precipitated as hydi-ate, with free
sulphur, which may be washed, dried, ignited and weighed as
alumina. The boiling until all sulphur smell is gone is a tedi-
ous operation, and the following modification is said to give
equally accurate results : To the slightly acid solution, sodium
thibsulphate is added more than equivalent to the arhount of
free acid present. The liquid is then boiled in a flask 10 to 15
minutes. The precipitated alumina is in a fine, granular state,
easy to wash. The liquor is rapidly filtered, the precipitate
washed with boiling water, dried, ignited and weighed.
A great disadvantage of the foregoing method is that any
phosphoric acid present in the solution will be precipitated
with the alumina. With certain iron alloys this would materially
afifect the result. To overcome this disadvantage, Mr. Peters
suggested converting the alumina entirely into phosphate, still
keeping the same method of separation from iron. The pro-
cess, as mbdified, is as follows : If less than one gramme of
iron is in the solution, it is diluted to 400 or 500 c.c. with cold
water, and ammonia added until the solution is dark-red in
color but contains no precipitate. Now add 3 c.c. of hydro-
chloric acid (sp. gr. 1.2), and 2 grammes of sodium phosphate,
dissolved in water and filtered. Stir till the precipitate formed
is re-dissolved and the solution is clear. Add now 10 grammes
of sodium hyposulphite dissolved in water and 1 5 c.c. of acetic
acid (sp. gr. 1.04), heat to boiling, boil 15 minutes, filter as
rapidly as possible, wash with hot water, dry, ignite in a porce-
lain crucible raising the heat very carefully until all the carbon
has burnt ofif, and weigh as AlPO^ (Al.Oa.P.O^).*
Mr. R. T. Thompson, an English chemist, stated that he
found Chancel's separation ineffectual in determining alumin-
ium in presence of large, quantity of iron (probably mainly be-
cause of the phosphoric acid present), and devised the follow-
ing method of separation : The iron is reduced to the ferrous
state by a current of sulphurous acid gas, excess of this gas is
*The Chemical Analysis of Iron, A. A. Blair.
620 ALUMINIUM.
boiled off, and when cool, phosphoric acid or sodium or am-
monium phosphate is added in excess of that required to pre-
cipitate all the alumina, then aqua ammonia until a faint
permanent cloudiness is formed, finally excess of ammonium
acetate. The precipitate generally contains a little iron, but
on washing it, re-dissolving in acid and repeating the precipita-
tion, it is obtained free from iron. The precipitate is dissolved
in hydrochloric acid, a little nitric acid added, boiled, and
nearly neutralized with caustic soda, and then boiled with an
excess of the latter. The aluminium is precipitated as phos-
phate, is washed with a i per cent, solution of ammonium
nitrate containing about O.i gramme of ammonium di-hydric
phosphate per litre, and ignited and weighed as aluminium
phosphate. *
A method of separation which has given the writer satisfactory
results is the following :f To the cold, concentrated and slightly
acid solution add an excess of solid sodium bi-carbonate in
such quantity that after stirring a little remains undissolved and
all the iron appears to be thrown down. Now add solution of
potassium cyanide until the precipitate dissolves, then heat
gently until the yellow color of potassium ferro- cyanide is pro-
duced. Add a few drops of caustic potash to the somewhat
turbid solution until it is perfectly clear ; then add excess of
ammonium chloride and boil. Aluminium hydrate is precipi-
tated free from iron, nickel or cobalt. As an analytical opera-
tion this method works very satisfactorily ; care must be taken,
however, in handling such large quantities of the very pois-
onous potassium cyanide.
It has been stated that if an excess of tri-methylamine is
added to a dilute solution containing iron and aluminium, and
let stand twenty-four hours, all the iron is precipitated and all
the aluminium remains in solution. f The accuracy of this sep-
aration has not been thoroughly tested.
* Journal, Society of Chemical Industry, V, 152.
t Chemical News, March 29, 1888.
J Zeitschrift fiir Anal. Chemie, xxiv, part 5.
ANALYSIS OF ALUMINIUM. 621
A. A. Blair recommends the determination of aluminium in
iron and steel (when it occurs in very small amount) by the
direct separation of ferric oxide from alumina, the method used
being as follows : Dissolve the iron in strong hydrochloric
acid, in a flask provided with a valve, thus keeping out air and
allowing the iron to dissolve in the ferrous state. Neutralize
with sodium carbonate, cool, dilute, add " milk" of barium car-
bonate, let stand several hours, the flask being meanwhile well
stoppered, and filter. The precipitate consists of all the alu-
mina, ferric oxide, chromic oxide, phosphoric acid or titanic
acid mixed' with the graphite and insoluble silica of the alloy.
Wash well, treat with dilute hydrochloric acid, boil the solution
with a slight excess of sulphuric acid, to precipitate the barium
in the solution. Settle, filter, wash with hot water and concen-
trate the solution by evaporation. To separate the iron from
the aluminium, add citric acid to the amount of five times the
weight of oxides present, and excess of ammonia. If the solu-
tion does not stay clear, acidulate with hydrochloric acid, add
more citric acid and excess of ammonia. Heat the clear solu-
tion to boiling and add fresh solution of ammonia sulphide until
all the iron is precipitated. Let settle, wash with water containing
ammonium sulphide. The iron sulphide can be dissolved in
acid and the iron thrown down with ammonia. The solution
can be acidified with hydrochloric acid, boiled, the sulphur fil-
tered out, evaporated to dryness, ignited, the residue fused
with sodium carbonate, dissolved in water, filtered, acidulated
with hydrochloric acid and the alumina precipitated by am-
monia. It would be quicker to take the solution containing
iron and aluminium and divide it into two portions. In one
part the iron and aluminium are thrown down together by am-
monia and weighed as oxides ; in the other the iron is sepa-
rated as above. The last part may then be omitted and the
aluminium found by difiference. The imperfection of this
method is the fact that the precipitate of alumina finally ob-
tained contains any chromic oxide, titanic oxide or phosphoric
acid that may be in the original solution. The first two ele-
622 ALUMINIUM.
ments may be seldom present, but some phosphorus is usually
present, and the alumina will be too high for this reason. If
the phosphoric acid is determined in this precipitate, this
source of error may be eliminated. A more serious defect,
however, is the fact that the iron is not completely precipitated,
as may be proved by small flakes of iron sulphide being de-
posited if the solution is let stand several days, showing that
the ammonium sulphide has the power of holding small quan-
tities of iron in solution. The aluminium results are thus apt
to be too high. Tartaric acid might be used instead of citric,
but it is more liable to contain alumina, and so gives results too
high in aluminium.
For separating large quantities of iron from small quantities
of aluminium, the electrolytic method seems to be particularly
applicable, for aluminium cannot be deposited from aqueous
solution by the battery (except under exceptional conditions
as alumina), while the iron can be totally deposited in a form
easy to weigh. This method of separation is equal in accu-
racy to any of the preceding chemical methods, and is not
difficult of application.
Dr. Classen gives the following method of procedure:* The
solution may contain iron, cobalt, nickel, zinc, and aluminium.
The solution of their sulphates is made very nearly neutral
with ammonia and an excess of ammonium oxalate added, so
that there are 2 or 3 grammes of this salt present to every o'.i
gramme of oxides. When the solution is not above 40° C. (its
volume is best 150 to 200 c.c.) it is electrolyzed with a current
not exceeding 10 or 12 c.c. of oxy- hydrogen gas per minute. If
the current is stronger than this, alumina may be precipitated.
If the amount of aluminium is not greater than that of the iron
(and other metals), this method gives accurate results. The
solution remaining is evaporated to dryness, heated gently to
decompose the aluminium salts, and finally ignited strongly to
alumina.
Prof. Edgar F. Smith gives an electrolytic method which for
* Quant. Chem. Analyse durch Electrolyse, p. 79.
ANALYSIS OF ALUMINIUM. 623
accuracy leaves nothing to be desired. * The solution of the
sulphates is made dilute, and about 10 per cent, of sodium ci-
trate and a few drops of citric acid added to it. This is elec-
trolyzed with a current of about 12 c.c. oxy-hydrogen gas per
minute, usingplatinum electrodes. The deposit of iron is firm,
and is washed successively with water, alcohol and ether, and
weighed. If the iron and aluminium have been already deter-
mined together, the« aluminium can be calculated by differ-
ence. If it is desired to weigh the aluminium directly, the
citric acid solution must be evaporated to dryness, ignited to
drive off organic matter, dissolved in acid, and the alumina pre-
cipitated by ammonia or ammonium sulphide.
Mr. John E. Stead of Middlesboro, England, has modified
Chancel's separation as follows, with very satisfactory results : t
The alumina is precipitated with sodium hyposulphite, thus
separating it from the bulk of iron. The precipitate is dissolved
on the filter in hot, dilute hydrochloric acid, and this solution
evaporated to dryness in a platinum dish. When dry, pure
caustic soda is put in, with a little water. After warming gently,
more water is added, the whole boiled five minutes and filtered.
The aluminium is precipitated in the filtrate by Peter's modifi-
cation of Chancel's precipitation, and the aluminium thus
weighed as phosphate, AIPO4 (22.13 per cent, aluminium).
The advantage of Stead's method is that it gives three dis-
tinct separations from the iron, thus completely eliminating it
from the final precipitate, while the addition of an excess of
phosphate causes the aluminium to precipitate quicker and
more completely. Comparisons of the different methods for
determining small amounts of aluminium in iron have shown
this to be superior in accuracy to any other method.
Analysis of Aluminium Bronzes.
The ingredients usually present are copper, aluminium, silicon,
iron, and sometimes zinc, tin, nickel or lead. Solution in nitro-
* American Chemical Journal, 1888, p. 330.
t Journal Society of Chemical Industry, Dec. 31, 1889.
624 ALUMINIUM.
hydrochloric acid and evaporation to dryness will serve to sepa-
rate out the silicon as silica. If dissolved in hot nitric acid, the
tin remains in the residue as metastannic acid, which can be
ignited along with any silica remaining and weighed as stannic
oxide. The silica is left on treating this residue with hydro-
chloric or sulphuric acid, and its weight being subtracted from
the previous weighing gives the net weight of stannic oxide.
Lead would be precipitated from the nitris acid solution filtered
out above by nearly neutralizing the solution and adding a few
drops of sulphuric acid. The precipitated lead sulphate is
filtered out and weighed. Copper may be precipitated free
from zinc, iron or aluminium by evaporating the last filtrate
nearly to dryness, to drive off" nitric acid, acidulating with
hydrochloric acid and precipitating with sulphuretted hydrogen.
The precipitate of cupric sulphide may be mixed with sulphur
and ignited in a Rose crucible in a current of hydrogen and
weighed as cupric sulphide. Or, it may be dissolved in a few
drops of nitric acid (the least possible quantity), a few centi-
metres of sulphuric acid added and the solution electrolyzed.
The electrolysis of the solution can also be made directly in the
presence of iron and aluminium by using a sulphuric acid solu-
tion with only two or three drops of free nitric acid present.
The precipitation of copper by.the battery is advisable in many
respects, since the copper is simply removed from the solution
without leaving any reagent behind it, and the other metals can
be easily separated out of the solution remaining.
If the copper has been removed, either by sulphuretted hy-
drogen or by the battery, the solution contains only iron, alu-
minium, zinc, nickel or manganese. In the first case, it must
be oxidized by a little nitric acid and the precipitated sulphur
separated out. The metals remaining can be separated in sev-
eral ways ; the best, however, is to precipitate the iron and alu-
minium as basic acetates. To do this the solution is neutral-
ized with carbonate of soda until a faint precipitate forms, which
redissolves only after two or three minutes' stirring. Dilute,
add about 4 per cent, of acetic acid and excess of sodium ace-
ANALYSIS OF ALUMINIUM. 625
tate. Boil two or three minutes and then let the precipitate
settle. Wash quickly with boiling water containing a little so-
dium acetate. The filtrate contains all the zinc, manganese,
cobalt or nickel which were in the solution. The precipitate can
be dissolved in dilute hydrochloric acid and the iron and alu-
minium separated by any of the methods already given, prefer-
ably Peter's modification of Chancel's separation. The filtrate
may be evaporated to dryness, taken up with hydrochloric
acid, sodium carbonate added till a permanent precipitate just
forms, and then a drop or two of hydrochloric acid added to re-
dissolve this precipitatCj On passing sulphuretted hydrogen
through the solution the zinc is precipitated as sulphide, while
any manganese, nickel or cobalt present remain in solution.
When all the zinc is precipitated, allow to stand twelve hours,
filter, wash with sulphuretted hydrogen water, re-dissolve in
hydrochloric acid and throw down the zinc as carbonate by
sodium carbonate and ignite to oxide; or the zinc sulphide
may be mixed with sulphur, put in a Rose crucible and ignited
in a stream of hydrogen sulphide. It is in this case weighed as
sulphide.
If the solution from which the zinc has been precipitated and
filtered out be made strongly acid with acetic acid, and excess
of sodium acetate added, sulphuretted hydrogen may be passed
through again and will precipitate nickel or cobalt sulphides.
These are filtered out and the filtrate concentrated, ammonium
sulphide added to it, and then acetic acid. The remaining
nickel and cobalt will be precipitated. The two precipitates are
united and the nickel (and the cobalt if present) determined by
any of the ordinary methods of precipitation. The filtrate is
neutralized with ammonia, ammonium chloride added and let
stand at least 24 hours in order to precipitate out the manga-
nese as sulphide. Manganese might also be separated out of
the filtrate from the basic acetate separation by adding hydro-
chloric acid and boiling with bromine water. The manganese
is completely precipitated as dioxide.
If it is not wished to determine the copper, but only the alu-
40
626 ALUMINIUM.
minium present, the copper can be easily removed by adding a
slight excess of ammonia to the hot hydrochloric acid solution.
The solution is boiled a few minutes and filtered. The precip-
itate is apt to carry down and retain some copper. It is there-
fore necessary to re-dissolve it in acid and repeat the precipita-
tion. All the iron and aluminium are thus obtained in the
precipitate, along with manganese and possibly some zinc and
nickel, if these are present. The precipitate can be dissolved
in hydrochloric acid and the iron and aluminium precipitated
alone by a basic acetate separation.
Aluminium-Zinc Alloy.
The writer has several times had occasion to search for mi-
nute quantities of aluminium in zinc. The method which gave
complete satisfaction was as follows : Dissolve in nitric acid,
and separate out tin. Add sulphuric acid and separate out
lead. Make a basic acetate precipitation, and filter out the pre-
cipitated iron and aluminium. Dissolve in hydrochloric acid,
and precipitate the alumina with sodium hyposulphite, pre-
ferably adding sodium phosphate if the latter reagent on hand
is free from alumina. Using a large quantity of zinc for the
analysis, two analyses gave 0.004 srid 0.005 P^i" cent, of alu-
minium respectively, while a blank analysis to correct for alu-
mina coming from the reagents used gave absolutely nothing.
General Remarks.
In analyzing aluminium-tin alloys, hot nitric acid will dis-
solve the aluminium and leave the tin as meta-stannic acid.
Aluminium-silver alloys may be attacked by caustic alkali,
leaving silver undissolved in the residue, or may be dissolved in
hot nitric acid, nearly neutralized and the silver precipitated by
hydrochloric acid or sodium chloride. Alloys of aluminium
with either zinc, nickel or manganese are best analyzed by
bringing the alloy into solution and separating aluminium from
the other metal by a basic acetate precipitation. Aluminium-
lead alloys may be dissolved in hot nitric acid and the lead
ANALYSIS OF ALUMINIUM. '. 62/
precipitated by sulphuric acid after, nearly neutralizing the so-
lution and adding alcohol to it.
I would recommend that some qualitative tests such as are
suggested in the beginning of this chapter — blow-pipe tests,
wet tests, etc. — be always made preparatory to the quantitative
analysis ; and then, knowing what is present and which ele-
ments it is desired to estimate and which to neglect, the
method of attack and analysis should be decided on. Half an
hour spent in making qualitative tests and ten minutes in re-
flection as to the best method of analysis to adopt, will often
save several hours of unnecessary work, and frequently prevent
the exasperating necessity of having to stop an analysis and
start over again.
INDEX.
ACETYLENE, heat absorbed in the
formation of, 241
pure, cost of, 242
theoretical temperature at which
alumina should be reduced by,
241
Acid element, action of aluminium as
an, 99
hydrochloric, action of, on alu-
minium, 91, 92
nitric, action of, on aluminium,
90,91
resistance of aluminium to,488
sulphuric, action of, on alumin-
ium, 88-90
Acids, organic, action of, on alumin-
ium, 92-97
Adamson, Mr., on the use of ferro-
aluminium, 604
Air, action of, on aluminium, 83-85
-ships, use of aluminium in, 478
Alabama, deposits of bauxite in, 41
kaolin in, 49
Alkali Reduction Syndicate, Limited,
32
Alkalies, caustic, action of, on alu-
minium, 99, 100
double carbonate of aluminium
and the, 131
Alkaline carbonates, reaction of, on
neutral solutions of alu-
minium salts. 111
chlorides, solutions of, action of
aluminium on, 102 j
metals, reduction of, theoretically I
considered, 237 I
sulphates and carbonates, action |
of, on aluminium, 104
Allegheny river, aluminium works on '
the, 382 I
Alliance Aluminium Co., London,
England, 31, 32 '
cost of aluminium to i
the, 294 ;
plant of, 291 ]
Alloy, carboniferous, of aluminium,
403
Alloy, light, elastic, of aluminium, 538
Miller's anti-friction, 504
Alloys, aluminium, 492-533
analysis of, 606-627
aluminium-antimony, 495, 496
-arsenic, 497
-bismuth, 497
-boron, 497, 498
-cadmium, 498
-calcium, 498, 499
-chromium, 499, 500
-cobalt, 500
-copper, 534-571
general properties of,
534-536
groups of, 534
melting points of, 534-536
-gallium, 500, 501
-gold, 501-503
groups of, 493
-iron, 572-605
-lead, 503, 504
-magnesium, 504, 505
-manganese, 505, 506
analysis of, 626
-mercury, 506-509
-molybdenum, 509, 510
-nickel, 510, 511
analysis of, 626
-copper, 511-516
-phosphorus, 516, 517
-platinum, 517
practical production of, 492
-selenium, 519
-silicon, 517-519
-silver, 519-521
analysis of, 626
-sodium, 52]
specific gravity of, 494
-tellurium, 521, 522
-tin, 522-525
analysis of, 626
-titanium, 525-527
-tungsten, 527
-zinc, 528-530
analysis of, 626
-copper, 530-533
(629)
630
INDEX.
Alloys, for soldering aluminium, 461,
462, 464, 465
iron-alumiuium, Brin Bros', pro-
cess of preparing, 425
Cleaver's patent for pro-
ducing, 424, 425
Faraday and Stodart's
investigations on, 422,
423
' preparation of, by an alu-
min ium
compan y
in Ken-
tucky,
425, 426
by the Alumin-
ium Process
Co., 426, 427
ready-made, decline of the sale
of, 31
Almeta polish, composition of, 456
Alsite Aluminium Solder, 467
Alum and vitriols, separation of, 2
calcined, 128
discovery of process of obtain-
ing, 2
ignition of, with carbon, 403 j
investigations on the base of, 2 [
native, analysis of, 50, 51
Alumen, account of, by Pliny and
Columella, 1
derivation of the term, 1
Roccas, 1
Alumina, 112
action of carbon-bisulphide on,244
addition of, in the manufacture
of cast steel, 423
amorphous in aluminium, 59
amount of metal extracted from,
by the Hall process, 379
Billing's experiment on reducing,
in contact with iron, 424
change of, into its chloride, 242
conditions required for the re-
duction of, 238 i
cost of calcination of, 379
in Pittsburg, 379
data for the decomposition of, 239 :
Davy's experiment to decompose, 1
319 '
decomposition of, by the electric
current, 5 !
effect of, on steel, 577 1
electro-motive force required to
decompose, 302
equation for the temperature at
which hydrogen gas will
begin to reduce, 240
Alumina, equation for the voltage re-
quired to decompose, 239
formula for finding the tempera-
ture at which reduc-
tion of, by carbonic
oxide begins, 240
the heat required to de-
compose, 239
hydrated, precipitation of, 133
impossibility of the reduction of,
by the ordinar3' reagents, 230
liquefaction of, 231
rnanufacture of, by Bergius, 379
native sulphate of, 50, 51
not reduced by sodium or potas-
sium, 230
occurrence of, in plants, 39, 40
preparation of, for reduction, 133-
152
reduction of, by carbon, 231,240,
241,415
hydrogen, 231, 240,
241, 407
magnesium, 229, 230,
437, 438
theoretical aspect of the reduc-
tion of, 229
temperature at which acety-
lene should begin to re-
duce, 24J
various names for, 2
Aluminate of soda, precipitation of
alumina from, 143
Aluminates, 109, 110
properties of the various, 114,115
Aluminite, 127
Aluminium, action of air on , 83-85
alkaline sulph-
ates and car-
bonates on,104
ammonia on, 100
bromine on, 106
caustic alkalies
on, 99, 100
chlorine on, 106
cryolite on, 103
fiuorine on, 106
fluorspar on, 102,
103
hj-drochloric
acid on, 91, 92
hydrogen on,106
iodine on, 106
lime water ou,
100
nitre on, 104
nitric acid on,
90,91
INDEX.
631
Aluminium, action of on baryta, 105
carbonic ox-
ide, 106
copper oxide,
.105
solutions,
101
ferric oxide,
105
lead oxide, 105
solutions,
101,102
manganese di-
oxide, 105
oxide, 436
mercu reus
chloride,
106
mercury solu-
tions, 101
metallic o x -
ides, 105,
106
silver c h 1 o -
ride, 106
solutions of al-
uminium
salts, 102
of metallic
chlorides,
102
zinc oxide, 105
solution, 102
organic acids,
vinegar,
etc., on, 92-
97
secretions on,
98,99
phosphate of
lime on, 106
sea-water on, 97,
98
silicates andbor-
ateson,103,104
silver solutions
on, 101
sodium chloride
on, 97,98
solutions of me-
tallic salts on,
100-102
sulphuric acid
on, 88-90
water on, 85, 86 <
alloys, 492-533
Bamberg's method of pre-
paring, 427
Aluminium alloys, groups of, 493
H^roult's process of
producing, 388
practical production
of, 492
amalgam, preparation of, 507
properties of, 508, 509 1
-ammonium chloride, 117, 118
amorphous alumina in, 59
amount of, produced, 35-38
analyses of, 53-56
and specific gravities of, 63
and aluminium alloys, analysis
of, 606-627
carbon, 123-125
nickel, electro-deposition of
an alloy of, 31 1
sodium, double sulphide of,
177
anhydrous silicates of, 49
annealing of, 452
antimonate, 130
-antimony alloys, 496, 496
apparatus for obtaining, 311
-arsenic alloys, 497
articles, polished, tarnishing of,
98, 99
as a base and as an acid, 109
atomic weight of, 83, 301
basic salts of, 110
Basset's process for obtaining,
429-431
bell cast of, 67, 68
Benzon's patent for the reduction
of, 414, 415
Bessemer's process for producing,
404, 405
-bismuth alloys, 497
borate, 131, 132
bolides, 122, 123
-boron alloys, 497. 498
boron-carbide in, 59
Brass and Bronze Co., of Bridge-
port, Conn., 28
brasses, 530-533
forging capability of, 533
tests of, 531 , 532
Braun's process for depositing,
310, 311
bromide, 118
heat developed in the forma-
tion of, 232
bronze, annealed, resistance of,
560
brazing of, 569
Brin's process for producing,
417,418
casting of, 548-552
632
INDEX.
Aluminium bronze, Clark's patents for
preparing, 434
dilution of a high per
cent., to a lower one,
547
Evrard's process for
producing, 414
Faurie's process for
preparing, 415, 416
Hampe's experiments
in producing, 290
history of the applica-
tion of, 539
Mann's patent for pro-
ducing, 417
mechanical properties
of (6per cent.), 537
prices of, 35
soldering of, 569, 570
bronzes, 538-571
analysis of, 623-626
annealing and hardening of,
561
anti-friction qualities of, 563,
664
color of, 552, 553
compressive strength of, 554,
555
conductivity of, 564
constitution of, 540-545
diagram of the variation of
tensile strength and elong-
ation of, 559, 560
fusibility of, 548
hardness of, 553, 554
melting points of, 548
preparation of, 545-547
prices of, 539, 540
resistance of, to corrosion,
564-567
role of aluminium in, 542, 543
specific gravity of, 553
tensile strength of, 555-561
transverse strength of, 554
uses of, 567-569
working of, 561, 562
Bucherer's process for producing,
400, 401
Bull's process of manufacture, 314
Burghardtand Twining's process
for depositing, 314, 315
burning of, 84, 85
cab, 478
-cadmium alloys, 498
-calcium alloys, 498, 499
Calvert and Johnson's experi-
ments on the reduction of, by
iron, 420, 421
Aluminium carbide, process of prepar-
ing, 124
properties of, 124, 12.5
carbon required for the produc-
tion of, 378
carbonate, 131
carboniferous alloy of, 403
casting of, 445-447
castings, hardening of, 453
chemical equivalent of, 301
chemically pure, preparation of,
451
chloride, 115, 116
and aluminium-sodium chlo-
ride, preparation of, 152-
168
anhydrous, preparation of,
152
apparatus for the continuous
electrolysis of,
354
preparation of,
used at Salin-
dres, 157-159
calculated difference of po-
tential, for the dissociation
of, 369
calories required for the de-
composition of, 369
Deville's methods of reduc-
ing, by sodium, 252-257
electro- motive force necessary
to decompose, 302
graphic formulae of, 108, 109
heat developed by the com-
bination of some of the
elements with, 232
heat for formation of, 242,
243
inconveniences of the reduc-
tion of, 275
molten, decomposition of,
.398
or aluminium-sodium chlo-
ride, methods based on the
reduction of, 246-300
purification of, 156, ].57
reduction of, by battery, 10
by magnesium,
437
by tin, 439
the vapor of, b)'
zinc, 435
voltage required to decom-
pose, 238
-chlorphosphydride, 118
■chlorsulphydride, 118
-chromium alloys, 499, 50O
INDEX.
633
minium, cleaning and pickling of,
Aluminium compounds, Monckton's
456
patent for reducing.
clippings, filings, etc., melting
by the battery, 3k5
of, 442, 443
Netto's process of re-
coating iron work of the tower
ducing, 290-294
of the Philadelphia Public
Oersted's experiments
Buildings with, 316, 317
in reducing, 246, 247
metals with, H07, 308, 469-472
Percy and Dick's ex-
-cobalt alloys, 500
periments in reduc-
color of, 59, 60
ing, 283-285
combinations of, 39
preparation of, for re-
Comenge's process for producing,
duction, 133-178
411
properties and prepar-
commercial, average strength of.
ation of, 107-132
73
reduction of, by electri-
carbon in, 57, 58
city ,236,
elements to be sought for in,
301-401
606
by means
impurities in, 52
of po-
nitrogen in, 58, 59
tassium
testing of, with the knife, 62
and so-
Co., Ivimited, bronzes containing
dium,
nickel made by the.
246-300
512-515
by Nie-
incorporation of the, 23
werth ' s
works of the, 212, 270,
process.
271
268
Neuhausen, sheet aKiminium
by other
made by the, 465, 466
means
comparison of actual and atomic
than so-
specific heats of, 80
d i u m
of production of, with other
and el-
metals, 38
ect rici-
compounds, appearance of, 40
ty, 402-
jehavior of, before the blow-
441
pipe, 111
from the
Deville's experiments in re-
stand-
ducing, 250-252
point of
methods of reducing.
thermal
285-287
c hemis-
Deville-Castner process for
try,226-
the reduction of, 270-273
245
formulse of, 40
Minet 's
Frishmuth's process for the
views
reduction of, 269,' 270
on the.
Gadsden's patent for the re-
358
duction of, 269
Rose's experiments in
general methods of formation
reducing, 274-283
and properties of, 110, 111
structure of, 108-110
Gerhard's furnace for the re-
Thompson and White's
duction of, 289
patent for the reduc-
Grabau's process of reducing.
tion of, 290
294-300
Tissier Bros', method
Grousillier's improvement
of reducing, 287, 288
in the reduction of, 270
voltage required to de-
Le Chatellier's method of
compose, 237
reducing, by the battery.
Wohler's experiments
324, 325
in reducing, 247-250
634
INDEX.
Aluminium, compressive tests of, 72
cooking utensils, advantages of,
485, 486
-copper alloys, 534-571
general properties of,
534r-53(i
groups of, 534
melting points of, 534-
536
Corbelli's patent for producing,
410
process for depositing, 308
corrosion of, 84
cost of, 379, 380, 381, 382
by the Deville process,
267, 268
-Castner pro-
cess, 273
H&roult pro-
cess, 397
by Netto's processes, 294
Cowles Bros', process of produc-
ing, 329-347
Crown Metal Co., 22
crucibles for melting, 103, 104
crystalline form of, 69
crystallization of, 282
cyanide of, reduction of b}' zinc,
433, 434
decomposition of silver sulphide
by, 87
decorations of, 479
density of, increa.sed by being
worked, 63
dental plates, action of saliva on,
98
deposition of, from aqueous solu-
tion, 307-318
determination of, in aluminium
bronze, 624
does the, remain in iron castings ?
598, 599
drawing of, 454
ductility of, 76. 77
dust, 76
earl}' production of, by electro-
lytric methods, 11
effect of alloying on the color of,
493
carbon on the physical
properties of, 58
nitrogen on, 58, 59
on steel, 575-581
on wrought-iron, 581-595
purity of, on the amount
of heat in, 80
effects of impurities in, 52
elasticity of, 69, 70
Aluminium, electric conductivity of,
81,82
electro-chemical equivalent of,
301
-deposition of, various pat-
ents for, 315
Emanuel's process for producing,
406
engraving of, 456
exhibit at the Columbian Expo-
sition in Chicago, 1893, 34
of, at the Paris Exposition,
1855, 13
expansion of, by heat, 77
Farmer's patent for producing,
347
Faure's proposition to obtain,
398, 399
Feldman's method of producing,
362, 363
-ferro-silicon, claims for, 595, 596
manufacture of, 427
films, color of, by transmitted
light, 60
first article made of, 13, 474, 475
experimenter on the isolation
of, 3
Fleury's process for producing,
408
fluorhydrate, 120
fluoride, 119
affinity of, for sodium fluor-
ide and potassium fluoride,
275
and aluminium-sodium fluor-
ide (cryolite), preparation
of, 168-173
reduction of, 235
by sodium, 294-300
fracture of, 60, 61
freeing of, from impurities, 449-452
fusibility of, 65, 66
fusion of, latent heat of, 79,80
-gallium alloys, 500, 501
gases in, 57
Gaudin's patent for reducing, 325
Gerhard's process for producing,
406, 407
-gold alloys, 501-503
Gore's process for depositing,
308, 309
Grabau's apparatus for produc-
ing, 364, 365
process of producing, 400
Gratzel's process of producing,
326-329
Green's process of producing,
409, 410
INDEX.
635
Aluminium, grinding, polishing and
burnishing of, 455, 456
Hall's process of producing, 372-
386
hardening of, 452, 453
hardness of, 61, 62
heat generated by the combina-
tion of, with the different
elements, 228
required to melt, 81
Hferoult's process of producing,
386-398
high value of the specific heat
of, compared with other metals,
81
history of, 1-38
hollow-ware, cast, for culinary
use, 447
hydrates, 113
-hydrogen fluoride, 120
immense future of, 474
improving the quality of, 449
impure, phenomena in melting,
442
purifying of, 295
Industrie Actien Gesellschaft, 30
organization and
plant of, 393, 394
patent of the, 401
industry at the Paris Exposition,
1889, 33
in 1859, 263. 264
possible lines of improve-
ment in the, 20
progress in the, 33, 34
reactions of use in the, 242-
245
revolutions in the, 24
statistics of the, 34-38
\V. Weldon on the prospects
of the, 20, 21
influence of, in puddling iron,
594, 595
flux or slag on the,
253
on cast-iron, 595-605
the vessel on, 253
in the soot from Cowles Bros'.
furnace, 343
iodide, 118, 119
heat developed in the forma-
tion of, 232
-iron-alloys, 572-605
melting point of, 588
isolation of, 8
Jeancon's process for depositing,
309, 310
kaolin the natural ore of, 49
Aluminium, Kagensbusch's process
of reducing, 325
Kleiner's process for producing,
347-353
Knowles' patent for producing,
410
latent heat of fusion of, 79, 80
-lead alloys, 503, 504
leaf, 76
beating and tempering of, 454
decomposition of, in water, 86
superiority of, 479
Lebedeff's process of producing,
409
loss of, by oxidation during re-
duction, 280, 281
Iiossier's method of producing,
353, 354
-magnesium alloys, 504, 505
magnetism of, 67
malleability of, 75, 70
-manganese alloys, 505, 506
analysis of, 626
mat on, 456
mechanical tests of, by the Pitts-
burgh Reduction
Co., 7(1-72
value of, 74
melted, improvement in, b}' blow-
ing air into it, 451
melting of, 442-445
point of, 65, 66
Menge's patent for producing,
347
-mercury, alloys of, 506-509
metallic, occurrence of, 39
sulphates, 129
meta-phosphate, 131
method of obtaining, patented
by H. A. Gadsden, 164
military uses of, 475, 476
Minet's electrolytic process of
producing, 354-362
miscellaneous uses of. 490, 491
molten, absorption of gases by,
57
peculiarity of, 446
-molybdenum alloys, .509, 510
Montegelas' patents for deposit-
ing, 312, 313
Morris' process for producing,
405, 406
naval use of, 476-478
necessity of using pure materials
in the production of, 252
-nickel alloys, 510, 511
alloys, analysis of, 626
-copper alloys, 511-516
636
INDEX.
Aluminium, Niewerth's patent for the
reduction of, by iron, 418,
419
process for producing, 411-
413
nitrate, 130
nitride, 125, 12(5
non-aqueous electric processes of
depositing, 318-401
normal and neutral salts of, as a
base, 110
object of alloying, 493
objections to the term. 5, 0
occurrence of, in nature, 39-51
odor of, 66, 67
origin of the term, (i
output of, by the Hall process, 383
Overbeck and Niewerth's process
for depositing, 311, 312
oxidation of, 84, 85
oxide, 112
graphic formulae of, 108, 109
passementerie, 76
Pearson, Liddon and Pratt's pat-
ent for producing, 404
percentage of, in the earth's
crust, 39
perfectly pure, Deville's method
of obtaining, 252
Petitjean's process for produc-
ing, 408, 409
phosphates, 130, 131
-phosphorus alloys, 516, 517
chloride, 117
physical properties of, 52-82
plating of, on copper, 323, 324
on, 472, 473
-platinum alloys, 517
position of, in the periodic clas-
sification of the elements, 107,
108
powder of, influence of pressure
on, 66
precipitation of, by magnesium,
437
prices of, 14, 15, 17, IS, 20, 35
Process Co., of Washington, D.C.,
iron-aluminium alloys manu-
factured by, 42(>, 427
proportion of, extracted from
cryolite, ,351
pure, HSroult and Kiliani's ap-
paratus for producing, 394
impossibility to manufacture,
direct from minerals con-
taining silica, 103
purest commercial, analysis of,
451
Aluminium, purification of, 447-452
purity of, produced by Kleiner's
process, 352, 353
quality of, produced by Minet's
process, 361
racing sulkies, 478
railway carriage, 478
rationale of the action of, on cast
iron, 605
reaction according to which cry-
olite dissolves, 372
reasons for blue tint of, being
more prominent
after working the
metal, 60
its being difficult to
solder, 457, 458
reduction of, in the iron blast
furnace, 429
Reillon, Montague and Bourger-
el's patent for producing, 409
Reinbold's recipe for depositing,
312
relative cost of materials in mak-
ing, 20
removing discoloration from arti-
cles of, 60
researches of H. St. Claire De-
ville on, 9-16
retrospect of the art of working,
18, 19
Rogers's process of producing,
365-368
rolling of, 453, 454
salts, decomposition of, in aque-
ous solution, 304
reactions of neutral solutions
of, HI
solutions of, action of alu-
minium on, 102
second quality, analyses of, 381
selenide, 122
selenites, 129, 130
-selenium alloys, 519
chloride, 117
vSenet's process for depositing,
311
Seymour's patent for the reduc-
tion of, by zinc, 432, 433
silicates, 132
-silicon alloys, 517-519
silver, 516
alloys, 519-521
analysis of, 626
-sodium alloys, 521
chloride, 116. 117
and aluminium chloride,
preparation of, 152-168
INDEX.
637
Aluminium-sodium chloride, Bunsen 's
and Deville's
methods of de-
composing, by
the battery,
320-324
cost of, 159, 164
largest plant
erected for the
manufacture
of 159-162
method of pre- \
paring, 278. I
279 ■ j
quantities of ma-
terials used in
the prepara- j
tion of 163
o r aluminium
chloride.meth- '
ods based on 1
the reduction i
of, 246-300 j
reduction of, by |
sodium,
265-268 I
by zinc, 429
fluoride, 120, 121
(cr3-olite) and alu-
minium fluoride,
preparation of,
168-173
lining of, 296
soldering of, 457-469
solution of, by molten cryolite,371
sonorousness of, 67-69
specific gravity of, 62-65
when molten, 386
heat of, 77-81
stamping and spinning of 455
suitability of, for culinary uten-
sils, 96, 97
sulphate, 126, 127
or alunjs, preparation of
alumina from, 133-137
sulphide, 121, 122
decomposition of, by anti-
mony and carbon, 438
electrolysis of 400, 401
heat for combination of, 244
Lisle's experiments in reduc-
ing, by zinc, 435
preparation of, 174-178
reduction of, by copper, 417
iron, 418
thermal relations of, 2.S5, 236
voltage required to decom-
pose, 238
Aluminium-sulphur chloride, 117
superiority of, for constructions,
75
taste of, 67
-tellurium alloys, 521 , 522
tendency of, to absorb gas, 452
tensile and compressive strength
of 70-75
strength of, affected by an-
nealing, 74
tests of, 7]
thermal conductivity of, 82
Thompson's process for deposit-
ing, 308
manufac-
ture of,
419,420
Thowless' proposition to pro-
duce, 403,404
-tin alloys, 522-525
analysis of, 620
melting points of, 524,
525
-titanium alloys, 525-527
torpedo boat of, 477
transverse tests of, 72
tri-valency of 109 .
tubes, manufacture of, 454
-tungsten alloys, 627
und Magnesium Fabrik at Hem-
eliugen, 24
Magnesium Fabrik, tests of
aluminium brass by the,
532
Magnesium Fabrik, works of
the, 328
use of, for batteries, 487, 488
chemical apparatus,
484, 485
coinage, 483, 484
constructions, 487
culinary utensils, 485,
486
flash light powder, 489.
490
lithographic plates,
488, 489
ships, 97, 98
sounding boards, 68, 69
table ware, 486, 487
in aerial navigation, 478
German army, 96
Grove's batterj', 91
surgery, 98
uses of, 473-491
vapor, color of 66
variations in Rose's process of
preparing, 279
638
INDEX.
Aluminium, velocity of sound in, 69
volatilization of, 66
Walker's patents for the electro-
deposition of, 313, 314
Warren's experiments in produc-
ing, 363, 364
welding of, 457
Willson's process for producing,
399
Winckler's patent for producing,
399
■wire, 76, 77
annealed, tensile strength
of, 73
tests of strength of, 70
worked and annealed, strength
of, 74
working in, 442-491
world's production of, 37, 38
Zdziarski's patent for producing,
364
-zinc alloys, 528-530
analysis of, 626
batteries, 488
-copper alloys, 530-533
Aluminous earths, manufacture oi
aluminium sulphate from, 127
fluoride slags, utilization of, 148,
149
pig iron, 414
Alumin-um, 6
Alums, 128, 129
or aluminium sulphate, prepa-
ration of alumina from, 133-137
Alunite, 128
Amalgam, aluminium, preparation
of, 507
properties of, 508, 509
American Aluminium Co., of Mil-
waukee, experiments of, 365-367
organization of the, 432
Amfreville, works at, 14
Ammonia, action of, on aluminium,
100
alum, 128, 129
Ammonium and aluminium, chloride
of, 117
reaction with, of neutral solutions
of aluminium salts. 111
Ampere, decomposing power of a
current of one, 301, 302
Analysis of alumiuium and alumin-
ium allovs, 606-627
-zinc alloy^ 626
quantitative, necessity of being
preceded by a qualitative anal-
ysis, 627
Andalusite, 49
Anderson, W., on the sodium works
at Oldbury, 212-215
tests by, of the strength
o f aluminium
bronze, 554, 555, 556
Andrews, G. F., on aluminium-gold
alloys, 501,502
on al uminium-
nickel-copper al-
loys, 516
Anhydrous aluminium sulphate, 126
Annealing aluminium, 452
and hardening aluminium
bronzes, 561
Anti-friction alloy. Miller's, 504
qualities of aluminium
bronzes, 563, 564
Antimonate of aluminium, 130
Antimony and aluminium, alloys of,
495, 496
reduction hy, 438
Aqua ammonia, reaction with, of
neutral solutions of aluminium
salts. 111
Arc, electric, reduction of disthene
in the, 319
Argil, 2
Arkansas, deposits of bauxite in, 41
Arsenic and aluminium, alloys of, 497
Atomic weight of aluminium, 83
Austria, deposits of bauxite in, 41
BAILLE and FSry on aluminium
amalgam, 507, 508, 509
Balances, alloy for beams of, 520
Balland, tests by, of the action of or-
ganic acids on aluminium, 94
Bamberg, G., alloys of aluminium
prepared by, 427
claims of, 435
Barium aluminate, 114, 115
salts, voltage required to decom-
pose, ^37
Barlow, W. H., on the tensile strength
of aluminium, 70
Baron, experiments of, on the isola-
tion of aluminium, 3
Baryta, action of aluminium on, 105
Base, action of aluminium as a, 109
Basic aluminium sulphate, 127
Basle, projected aluminium works
near, 395
Basset, M. N., process of, for obtain-
ing aluminium, 429-431
Bath, electrolytic, decomposition of
a, 306
Hall's, specific gravities of the
substances used in, 386
INDEX.
639
Bath-tubs, 447
Baths, composition and properties of
the, used in Minet's process, 357,
358
Batteries, use of aluminium for, 487,
488
Battersea, aluminium works at, 18
Battery, Grove, use of aluminium in
the, 91
use of, by Deville and Bunsen,in
decomposing aluminium com-
pounds, 320-324
Baudrin, P., alloy of, 512
Baur, J., alloys of, 531
Baux, bauxite from, 44
Bauxite, 40-45, 113
American, analyses of, 43
cost of, 41, 42
foreign, analyses of, 42, 43
French, composition of the typi-
ical kinds of, 44
important beds of, 41
imported, cost of, 41
Ivaur's process of calcining, 143
manufacture of aluminium sul-
phate from, 127
preparation of alumina from,
137-144
reaction of common salt on, 142
red, 44
Bauxites, American, analyses of, 45
constancy of the titanic
acid in, 45
Bayer, Dr. K. J., improvement in the
process of extracting alumina from
bauxite by, 143, 144
Beams, deck, of aluminium, 47S
Beer, action of, on aluminium, 95, 96
Behuke, process of, for preparing
alumina, 141
Beketoff, M., experiment of, 429
Bell Bros., aluminium plant of, 18
on drawing aluminium, 454
on Mourey's solders for alu-
minium, 461
Lowthian, experiment of, 410, 411
Bells, aluminium, 67
Benzon, patent of, 414, 415
Bergius, alumina manufactured by,
379
Berlin, Germany, aluminium works
at, 18
Bernard Bros., operation of Minet's
process by, 361
works of, 26
Berthaut's proposition, 326
Bertrand, M. A., electro-deposition of
aluminium by, 310
Beryllium aluminate, 115
Berzelius, experiments of, 6, 7
process for preparing artificial
cryolite, recommended by, 169
i Bessemer, H., Jr., process of, 404,405
' steel, eflfect of aluminium on, 578
; Bicycles, use of aluminium for, 478
! Biederman, R.,directionsby, formelt-
j ing aluminium, 443
on polishing alumin-
', ium, 455
on the preparation of
alumina, 148
Billings, G. H., alloy of aluminium
and carbon of, 575
experiment of, 424
Bismuth and aluminium, alloys of, 497
Blackmore, H. S., process of obtain-
ing sodium, patented by, 203
Blair, A. A., method of determining
aluminium in iron and
steel, recommended
by, 621, 622
on aluminium in steels,
575
Blast-furnace, occurrence of spinel
in the slags of, 115
reduction of aluminium in
the, 423, 429
Blow-holes, causes of, in wrought-
iron castings, 590-592
Blowpipe, behavior of aluminium
compounds before the. 111
Boats, tests of the suitability of alu-
minium bronze for, 566
Boisbaudran, L. de, on aluminium-
gallium alloys, 500, 501
Bolley, experiment of, 416
Bombay wootz steel, 422, 576
Boonton, N. J., works at, 31, 396
Borate of aluminium, 131
Borates and silicates, action of, on
aluminium, 103, 104
Bornemann, Dr. G., on the use of al-
uminium for chemical apparatus,
484, 485
Boron-aluminium bronze, 571
and aluminium, alloys of, 497, 498
compounds of, 122, 123
carbide in aluminium, 59
Bourbouze, M., on aluminium-tin al-
loys, 522
' process of, for sol-
dering aluminium,
463
Braces, aluminium, 480
Bradley and Crocker, retort, patented
by, 332, 333
640
INDEX.
Brandy, action of, on aluminium, 95
Brass, aluminium-tin alloy as substi-
tute for, 522
depositing aluminium on, 308,309
plating aluminium on, 469, 470
with, 473
Brasses, aluminium, 530-533
forging capability of, 533
tests of, 531, 532
Brauu, J., process of, for depositing
aluminium, 310, 811
Brazing aluminium bronze, 569
Bridgeport, Conn., works at, 31, 396
Brin Bros., preparation by, of iron-
aluminium alloys, 425
process of, for coating metals
with aluminium, 471
Iv. Q., process of, 417,418
Broadwell, H. C, process of, for coat-
ing sheet-iron with aluminium,
471,472
Bromide of aluminium, 118
Bromine, action of, on aluminium, 106
Bronze, analysis of a peculiar product
formed in the
furnace when
smelting for, 342
slags formed in pro-
ducing, 342, 343
boron-aluminium, 571
Cowles Bros., analyses of, 341
plating aluminium with, 473
phosphor-aluminium, 571
Richards', 533
silicon-aluminium, 570, 571 1
standard grades of, produced by .
the Cowles Co., 341
Bronzes, aluminium, 538-571
containing nickel patented by
J. Webster, 512-515 i
Brown, Lieut., experiments on alu-
minium for military use, 476
Bruner, process of, for preparing alu-
minium fluoride, 170 i
Briinner, experiments of, in making |
sodium, 180
method of, for making aluminium
fluoride, 119
Brush dynamo, dubbed the ' ' Colos-
sus," 339
Bucherer, process of, 400, 401
Buchner, G., on the treatment of alu-
minium containing silicon, 450
Buff-Dunlap washing apparatus, 147
Bull, H. C, manufacture of aluminium
proposed by, 314
Bullion, de-silverization of, by alu-
minium, 503
Bunsen and Deville, methods of, for
decomposing aluminium-sodi-
um chloride by the battery,
320-324
isolation of aluminium by elec-
trolysis by, 11
Burghardt and Twining, process of,
for depositing aluminium, 314, 315
Burnishing, polishing and grinding
aluminium, 455, 456
Butter, action of, on aluminium, 94
CAB, aluminium, 47S
Cadmium and aluminium, alloys
of, 498
Cailletet on the amalgamation of alu-
minium, 506
Calcined alum, 128
Calcium aluminate, 115
and aluminium, alloys of, 498, 499
Calvert and Johnson, experiments of,
on the reduction
of aluminium by
iron, 420, 421
on aluminium-iron
alloys, 573
process of, 413, 414
Candelabra, aluminium, 479
Canteens, aluminium, 475, 476
Carbon, action of, on alum, 403
and aluminium, 123-125
carbon dioxide, reduction by,
405, 406
bisulphide, heat of formation of,
245
reaction of, on alumina, 245
consumption of, in Hall's pro-
cess, 378
determination of, in aluminium,
616
dioxide, preparation of, 147
effect of, on the physical proper-
ties of aluminium, 58
formula for expressing the heat
in, 240
in aluminium, 53
non-wetting of, by molten cryo-
lite, 324
oxysulphide, heat of formation
of, 245
presence of, in commercial alu-
minium, 57, 58
reduction by, without the pres-
ence of other metals, 402-
405
of alumina by, 231 , 240, 241
in the presence
of copper,415
INDEX.
641
Carbonate of aluminium, 131
Carbonates, alkaline, action of, on al-
uminium, 104
Carbonic acid gas, precipitation of
alumina by, 147, ]4«
oxide, action of aluminium on 106
formula for finding the tem-
perature at which
reduction by, of
alumiua begins,
240
the heat of formation
of, 240
Carburetted hydrogen, reduction by
408-410
Carhart, Prof, on the thermal con-
ductivity of aluminium, 82
Caruelly, Prof, on the influence of
iron on the melting point of alu-
minium, 572, 573
Carroll, Dr. C. C, alloy of, for dental
plates, ri'IO
mode of casting al-
uminium by, 446
Casting aluminium, 445-447
bronze, 548-552
Castings, aluminium, addition of zinc
and copper to. 529
effect of copper on, 537
cast-iron, solidity ol, 597
iron, effect of the addition of ferro-
aluminium on. 59f>
mitis, absence of aluminium in,
587
history of, 582, 583
mixture for, 584
production of, 583
properties of, 586, 5S7
rationale of the process of
making, 587-594
raw material for, 583-585
strength of, 587
sharp, of aluminium, 446
wrought iron, causes for blow-
holes in, 590-592
Cast-iron, aluminium in, 423
aluminized, shrinkage of, 602,
603
castings, solidity of, 597
increase in the hardness of,
by aluminium, 603
influence of aluminium on,
595-605
rationale of the action of alu-
minium on, 605
Cast steel, addition of alumina in the
manufacture of, 423
Castner, H. Y., invention of, 22-24
41
Castner, H. Y., process, amount of alu-
niinium pro-
d u c e d by
the, 36
of, for the manu-
facture of so-
dium, 203-
217
for the reduc-
tion of so-
dium com-
pounds by
electricity,
223-225
for removing
iron from al-
um i n ium-
sodium chlo-
ride, 163
reduction of alumin-
ium by, 270-273
Caustic potash, reaction with, of neu-
tral solutions of aluminium
salts. 111
soda, electromotive force re-
quired to decompose, 304
molten, electrolysis of, 223-
225
reaction with, of neutral solu-
tions of aluminium salts,lll
Ceilings, aluminium. 479
Cliancourtois, M. de, on Greenland
cryolite, 286. 287
Cliandeliers, aluminium, 479
Chanu, M., founding of a works by, 14
Cbapelle, M., on the reduction by
carbon without the presence of
other metals, 402, 403
Chemical apparatus, use of aluminium
for, 484, 485
balances, aluminium for the
beams of, 482, 483
equivalent of aluminium, 301
properties of aluminium, 83-106
Chemistry, thermal, reduction of alu-
minium compounds from the stand-
point of, 226-245
Chenot, M., claim by, 10
experiments of, 421 , 422
Chicago, use of aluminium on a
building in, 487
Chiolite, 121
Chloride of aluminium, 115, 116
and sodium, manu-
facture of, 152-168
reduction of, theo-
retically consid-
ered, 232, 233 ■
642
INDEX.
CWoride, double, of aluminium and
sodium, reduction of, by zinc,
429
Chlorides, alkaline, solutions of, ac-
tion of aluminium on, 102
anhydrous metallic, preparation
of, 165, 166
heat developed by metals in
forming, 282. 233
metallic, solutions of, action of
aluminium on, 102
sodium or potassium, apparatus
for decomposing, 219
Chlorine, action of, on aluminium,
10(3
determination of, in aluminium,
616
gas, action of, on alumina, 112
qualitative test for, 6U6
Chrome-steel, aluminium in, 423,575
Chromium and aluminium, alloys of,
4i)9, 5U0
determination of, in alnminium,
617, 6KS
Chrysoberyl, 115
Church on alumina in plants, 39
Cider, action of, on aluminium, i)4
Clark, J., patents of, 434
Clarke, F. W. , on the percentage of
aluminium in the earth's crust, 39
Classen, Dr., method of, for deter-
mining aluminium in iron and
steel, 622
Clay, manufacture of aluminium sul- 1
phate from, 127 !
use of, for producing aluminium j
chloride, 167 i
Cleaning and pickling aluminivim, [
456
Cleaver, E., patent of, 424, 425 1
Cobalt and aluminium, alloys of, j
500 !
determination of, in aluminium j
bronze, 625 j
Coehn, recommendation of, in melt- i
ing aluminium. 452 t
Coffee, action of, on aluminium, 95, |
96 I
Coinage, aluminium, 483. 484
requirements of a metal for, 483.
484
Color of aluminium, 59. 60
alloys, 498
vapor of aluminium, 66
Colorado, cryolite in, 46
native alum in, 50
Columbian Exposition, Chicago, 1893,
aluminium exhibit at the, 84
Comenge, M., on the reduction of
aluminium sulphide
by copper, 417
on the reduction of
aluminium sulphide
by iron, 418
preparation of alumin-
ium sulphide pro-
posed by, 177
process of, 411
Compass boxes, aluminium, 482
Compounds of ahiminium, structure,
properties and pre-
paration of, 107-
132
voltage required to
decompose, 287
Conductivity, electric, of aluminium,
81,82
thermal, of aluminium, 82
Constructions, use of aluminium for,
487^
Cooking utensils, aluminium, 476
use of aluminium for, 485
Cooper, W. S., castiugs of aluminium,
made by, 447
Copper alloyed with aluminium, pro-
duction of, 413, 414
aluminate, 115
and aluminium, alloys of, 534-571
depositing aluminium on, 308,
309
determination of, in aluminium,
614
bronze,
624
effect of a small percentage of,
on aluminium, 536. 537
on the color of alumin-
ium, 59
malleability of alu-
minium, 537
elimination of, from aluminium,
449
heat of combination of, with alu-
minium, 543. 544
nickel and aluminium, alloys of,
511-516
oxide, action of aluminium on,
105
plating aluminium on, 323, 324,
469, 470
with, 478
qualitative test for, fi06
reduction in the presence of, or
by, 418-418
of aluminium sulphide by,
236,417
INDEX.
643
Copper, salts, voltage required to de-
compose, 237
sheet on which aluminium has
been rolled, 473 *
solutions, action of aluminium
on, 101
zinc and aluminium, alloys of,
530-533
Corbelli, patent of, 410
process of, for depositing
aluminium, 308
Corbin on aluminium in chrome
steel, 575
Corrosion, resistance to, of alumin-
ium bronzes, 564
Corundum, 47, 4H
value of, 48
Cowles, A. H., aluminium-manganese
alloy of, 505, 506
on aluminium bronze
for heavy guns, 567,
568
Bros., aluminium-nickel-copper
alloys made by, 516
furnace of, aluminium in the
soot from, 343
process of, 329-347
furnaces used in the,
332-336
products of the furnace of,
341-343
reactions in the process of,
343-347
silicon-aluminium bronze of,
570, 571
test of aluminium brasses
made by, 531 , 532
useful effect of the current in
the process of, 344, 345
Co., bronzes, tests of, 554, 555,
556, 55i, 558
ferro-aluminium of the, 574
occurrence in the history of
the, 346, 347
on the resistance to corrosion
of aluminium bronzes,
565
solders for aluminium bronze
recommended by, 570
E. H. and A. H., 28
Electric Smelting and Alumin-
ium Co., 28
Electric Smelting and Alumin-
ium Co., infringement of the
Hall patents by the, 34
invention, 28, 29
process, principle made use of in
the, 28, 29
Cowles Syndicate Co., of England,
plant of, 340
Creil, France, works at, 26
installation of Minet's process at,
362
Cross and Hillebrand, description of
Colorado cryolite by, 46
Crucible steel, tests of the effect of
aluminium on, 580, 581
used in Heroult's process, 388,
390
Crucibles for manufacture of sodium,
208
melting aluminium, 103,
104, 443, 444
iron, used by Rose, 276, 277
lining for, 367, 444, 445
used at the Froges works, 395
Cryolite, 45-47, 120
action of, on aluminium, 103
quartz, 370
spiegeleisen, 436
advantages of, for reduction, 287,
288
amount of aluminium extracted
from, 367
artificial, preparation of, 169, 170
boiling of, in solution of soda, 168
commercial, impurities in, 295,
296
cost of, 46
decomposition of, in the wet way,
149-152
experiments on the use of, for
producing aluminium, 15
Gratzel on the electrolysis of,
369, 370
Hampe on the electrolysis of,
368-372
importation of, by the Pennsylva-
nia Salt Co., 46
manufacture of aluminium sul-
phate from, 127
methods based on the reduction
of, 274-300
molten, action of, on aluminium,
371
decomposition of, by mag-
nesium, 437
non-wetting of carbon by,
324
specific gravity of, 386
phosphoric acid in, 285, 286
preparation of, 168-173
of alumina from, 144-152
properties of, 45
proportion of aluminium ex-
tracted from, 351
644
INDEX.
Cryolite, pure, composition of, 46
purity of comuiercial, 367
quartz in, 870
recovering alumina from, 262
reduction of, ^85
advantages of the, 281
Woliler's modifica-
tions in the, 289
Schmidt on the electrolysis of,
308, 869
typical analysis of, 46, 47
use of, as a flux, 288
in Kleiner's process, 848,
34W
Wohler's modificalions of reduc-
ing, :iH9
Crystalline form of aluminium, 6!)
Culinary utensils, use of aluminium
for, 48.'), 486
Cunningham, Capt, patents of, 31
sodium processes of,
291.292
Cupellation of aluminium with lead,
459
Curaudau, production of potassium
or sodium by, 179, 180
Curie, P., process of making alumin-
ium chloride proposed by, 165
Current-density, influence of, 305
effect of the tension of the, 306
Cyanide of aluminium, reduction of,
by zinc, 433, 434
Cyanite, 49
Cyanogen, reduction by, 410, 411
DAGGER, H. T., on the Cowles
.process in England, 345
Darling, J. D., on the electro-deposi-
. tion of aluminium, 317, 318
Davenport, R. W., experiments of,
592^
experiments of,
with ferro-alu-
minium, 579,
oSO
explanation by,
of the effect of
aluminium on
wrought iron,
588, 589
Davy, Sir Humphry, experiment of,
to decompose
alumina, 319
experiments of,
4,5
isolation of so-
dium by, 179
Debray on aluminium bronze, 539
Decorations, use of aluminium for,
479
D'Eichthal, M., 15
"Defender," the, 478
Delaware, kaolin in, 49
Dental plates, alloy for, 520
aluminium for, 480, 481
cast aluminium, 446
of aluminium, 98
Dentistry, use of aluminium in, 481
Desilverizing process, addition of alu-
minium to the zinc used in the,
529, 530
Deville-Castner process, the, 24, 270-
273
cost of aluminium
by the, 273
H. St. Claire and Bimsen's meth-
ods of decompos-
i n g aluminium-
sodium chloride
by the battery,
320-324
composition of mix-
tures used by, 258,
261
controversy between,
and the Tissier
Brothers, 13, 14
experiments of, in
reducing alumin-
ium compounds,
250-252
first production of
aluminium fluor-
ide by, 119
improvements in the
manufacture of so-
dium by, 180-194,
197-201
method for deter-
mining silicon rec-
om mended by,
608, 609
method of, for de-
termining fluorine,
616,617
method of, for de-
term ining iron
(and aluminium),
611, 612
method of, for de-
termining sodium,
615, 616
method of, for pre-
paring alumina,
1.84, 135
INDEX.
645
Deville,H.St.Claire,methods of, based
on the reduction
of cryolite, 285-:i87
methods of, for re-
ducing aluminium
chloride by so-
dium. 252-1^57
on action of air on
aluminium, 83, 8-1
on action of caustic
alkalies on alu-
minium, 99
on action of nitre on
aluminium, 104
ou action of nitric
acid ou alumin
ium, 90
on action of organic
acids ou alumin-
ium, fi2, 93
on action of solu-
tions of metallic
salts on alumin-
ium, lUO, 101
on action of sul-
phuretted hydro-
gen on alumiuium,
80, 87
ou action of sul-
phuric acid on
aluminium, 88
on action of water
on aluminium, 85,
86
on aluminium-boron
alloys. 497, 498
on aluminium-lead
allovs, n{)3
on aluminium-mer-
cury alloys, 500
on aluminium-sili-
con alloys, 517,
518
on aluminium-sodi-
um alloys, 521
on aluminium-zinc
alloys, 528, 529
on casting alumin-
ium, 445
on color of alumin-
ium, 59
on crystalline form
of aluminium, 09
on effect of iron on
aluminium, 572
on freeing alumin-
ium from impuri-
ties, 449, 450
Deville, H. St. Claire, on freeing alu-
minium from slag,
447; 448
on fusibilitj' of alu-
minium, 05
on gilding and sil-
vering of alumin-
ium, 472
on melting alumin-
ium, 442, 443
on soldering alumin-
ium, 458, 459
on soldering alumin-
ium bronze, 509
on sonorousness of
aluminium, 07, 08
on veneering with
aluminium, 409,
470
on volatilization of
aluminium, 00
process for preparing
aluminium fluor-
ide recommended
by, 170
process for utilizing
aluminous fluoride
slags used by, 148,
149
process of amount of
aluminium made
by the, 30
process of for de-
composition of
cryolite in the wet
way, 149, 1.50
process of, for pre-
paring aluminium
chloride on a'sniall
and a large scale,
153-157
process of, for pre-
paring artificial
cryolite, 109,170
process of for reduc-
tion of aluminium
compounds, 257-
208
production of alu-
minium by, 8
researches of, on alu-
minium, 9-10
test by, of alumiuium
bronze, 5.56
work by, on alumin-
ium, 10
Dewar, Prof , on the relative electrical
resistances of metals, 82
646
INDEX.
Diaspore, 113
Dick and Percy, experiments of, 283-
285 •
Discoloration, removal of, from alu-
minium, 60
Disthene, 49
laminated, Duvivier's experiment
with, 319, 820
Ditte, A., on action of nitric acid on
aluminium,
90
sulphuric acid
on alumin-
ium, 88
water on alu-
minium, 86
Drawing aluminium, 454
Ductility of aluminium, 76, 77
Dufour, on the velocity of sound in
aluminium, 69
Dullo, M., on reduction of the double
chloride of aluminium
and sodium by zinc,
429
use of common clay for
producing aluminium
chloride, 167, 168
Dumas, M., on gases in aluminium, 57
Dust, aluminium, 76
Duvivier's experiment with laminated
disthene, 319, 320
Dyuamo-electric machinery, advances
in the, 24
machines, use of, first
proposed, 326
ELASTICITY of aluminium, 69, 70
Electric arc, reduction of disthene
in the, 319
conductivity of aluminium, 81,
82
current, mechanical and ther-
mal equivalent of the, 301
furnace. Mierzinski on the use
of the, 27, 28
Siemens', 27
lights, shades of aluminium
for, 479
processes, classification of non-
aqueous, 318
non-aqueous, of depositing
aluminium, 818-401
welding of aluminium, 457
Electricity, decomposing power of,236
reduction of aluminium com-
pounds by,
236, 301-401
Electricity, reduction of aluminium
compounds
by other
means than,
402-441
sodium com-
pounds by,
219-225
Electro-chemical equivalent of alu-
minium, 301
deposition of a metal, 304, 305
thermal methods, 318
Electrolysis of molten caustic soda,
223-225
sodium chloride,
222, 2:3
Elements, difierent, heat developed
by sulphur
combining
with, l35
generated by
the combi-
nation of al-
u m i n i u m
with, 228
heat given out by, combining en-
ergetically with oxygen, 229
position of aluminium in the
periodic classification of the,
107, 108
Elevators, use of aluminium on, 479
Ellery-Howard Co., New York, use of
aluminium plates for printing by
the, 489
Emanuel, P. A., process of, 406
Embroidery, aluminium in, 475
Engineering instruments of alumin-
ium, 482
England, amount of aluminium pro-
duced in, 36
first aluminium works in, 18
kaolin in, 49
Engraving aluminium, 456
Equivalent, chemical, of aluminium,
801
electro-chemical, of aluminium,
301
Escher, Wyss & Co., aluminium ves-
sels built by, 476
Ettmiiller, discovery by, 2
Eureka Tempered Copper Co., claim
of the, 458
Evrard, M., production of aluminium
bronze by, 414
FALLS OF THE RHINE, alumin-
ium works at, 388
Farmer, M. G., alloy of, 531
INDEX.
647
Fanner, M. G., apparatus patented
by, for obtaining
aluminium elec-
trically, 311
patent of, 347
Faraday and Stodart, aluminium-iron
alloy obtained by,575
investigations of, on
iron-aluminium al-
loys, 422, 423
on sonorousness of alu-
minium, 6S
thermal conductivity of
aluminium, 82
Faure, C. A., process for producing
aluminium chloride
patented by, 166,167
proposition of, 398,
399
Faurie, G. A., claim of, 413
process of, for prepar-
ing aluminium
bronze, 415, 416
Faustman & Ostberg Mitis Foundry,
experiments at the, 577
Feldman, A., method of, 362, 363
Felsobanyte, 127
Ferric oxide, action of aluminium on,
1115
Ferro-aluminium, 574
analyses of, 342
-aluminium, analysis of slags
formed in producing, 342
claims for, in foundry use,
595, 596
effect of, on the grain of iron,
601 , 602
increase in elasticity of iron
by the addition of,
60(1, 601
in fluidity of iron by,
602
in hardness of iron
by, 603
in transverse
strength of iron
by the addition oi,
699, 600
manufacture of, 425
mode of adding to iron, 596
practical benefit to poor iron
from, 603-604
results of adding, to iron,
605, 606
reduction in the shrinkage of
iron by, 602, 603
-aluminiums, analysis of, 618-623
Field glasses, aluminium, 481
Films of aluminium, color of, by
transmitted light. 60
Findlay, Ohio, plant at, 432, 433
Fischer, Dr. P., on Braun's process for
depositing alu-
minium, 311
Gratzel's patent
claims, 328
Fizeau on the expansion of aluminium
by heat, 77
Flash-light powder, use of aluminium
for, 489, 490
Fleury, A. L,., process of, 408
Fluoride of aluminium, reduction of,
theoretically considered, 234, 235
Fluorides of aluminium, 119-120
role of, as a flux, 257, 258
table of the heat of formation of,
234
Fluorine, action of, on aluminium, 106
determination of, in aluminium,
616, 617
gas, action of, on alumina, 112
isolation of 234
Fluorspar, action of, on aluminium,
102, 103
Flux and slag, influence of, on the
aluminium, 253
Foods, action of on aluminium, 94, 96
Forks, aluminium, 486
Fowler, Dr., patent of, for using alu-
minium in dentistr3', 481
Fracture of aluminium, 60, 61
France, aluminium industry, in 19,20
amount of aluminium produced
in, 36
bauxite in, 41
kaolin in, 49
operation of the Hall process in,
362
Fremy, M., on the preparation of al-
uminium sulphide, 174-176
French Guiana, deposits of bauxite
in, 41
Frishmuth, Col. Wm., aluminium man-
ufactured by,
32,33
electro-de posi-
tion of an alloy
of nickel and
aluminium by,
311
process of, 269,
270
solders of, for al-
uminium, 462
Froges (IsSre), France, works at,
30, 395, 396
648
INDEX.
Fruits, juices of, action of, ou alumin-
ium, 96
Furnace, Cowles Bros'., ?.R4-H?S
aluminium in
the soot
from, 34S
products of
the, 341-343
electric, Mierzinski ou the use of
the, -27, 28
peculiar product formed in
tne, 499
for continuous manufacture of
sodium in cylinders, 191,
192
mitis castings, 585. 586
production of sodium, 2(i8
Gerhard's, 289
Grabau'sf 298
Gratzel's, 326, 327
Niewerth's, 411, 412
Oni holt's, ;h64
reduction, 266
reverberatorj-, melting alumin-
ium in the, 444
Siemens' electric. 27
Thomson's, for preparing alu-
mina from cryolite, 144, 145
used in Heroult's process, 388,390
Fusibility of aluminium, 65, 66
Fusion of aluminium, latent heat of,
79, 80
GADSDEN, H. A., method of ob-
taining alu-
minium pat-
ented by, 164
patent of, 269
Gabnite, 115
Galanaugh, aluminium rowing .shells
of, 478
Gallium and aluminium, alloys of,
500, 601
Galvanizing bath, aluminium-zinc
alloy as an addition to the, 5l9
Gas, absorption of, by aluminium, 452
-fixtures, aluminium, 470
Gaudin, process of, for reducing alu-
minium, 325
Gehring, Dr. G., method of, for coat-
ing metals, stoneware, etc., with
aluminium, 471
Geoffroy on the base of alum, 2
Georgia, bauxite in, 41
Bauxite and Mining Co., 41
kaolin in, 49
Gerhard, F. W., furnace of, 289
process of, 406, 407 I
Gerhart, C. H., aluminium works of,
18
German armv, use of aluminium in
the, 96
-silver, alloy of, with aluminium,
538
depositing aluminium on,
308, 309
Germany, aluminium industry of, 18
Gibbsite' 113
Gilchrist, P. A., investigations of, on
aluminium in steel, 579
Gilding aluminium, 472
Glaciere, works at, 15
Gmelin on the amalgamation of alu-
minium, 507
Gold and aluminium, alloys of, 501-
603
heat of combination of,
502, 503
Niirnberg, 5(11
plating aluminium with, 473
Gore, G., experiments of, 307
on electro-deposition of al-
uminium, 315
process of, for depositing
aluminium, 3*18, 309
Grabau, L,., advantages of the process
of, 299
apparatus of, 364, 365
electrolytic process of, 400
on electrolysis of molten
sodium chloride, 222,
223
patent of, for reducing
aluminium compounds
by phosphorus, 440, 441
patented improvements
of, 32
process of, 294-300
for producing
al u ni i n i u m
fluoride, 171-
173
Graphic formulae of aluminium com-
pounds, ](;8. I(i9
Gratzel, R., furnace used by, 326, 327
on the electrolysis of
cryolite, 369
patent of, 437
process of, 24, 326-329
Greene andWahl, patent of, for pro-
ducing pure me-
tal 1 i c manga ■
nese, 105, 106
production of pure
manganese by,
436
INDEX.
649
Greene, Dr., experiment of, 43()
Green, R. E., process of, 409, 410
Greenland, difficulties in obtaining
cryolite from, 28B
occurrence of cryolite in, 45
Grill-work, aluminium, 479
Grinding, polishing and burnishing
aluminium, 4o5, 456
Grove battery, use of aluminium in
the, 91
Grousillier, H. v., improvement of,
L'70
Griiner and Lau, on the reduction of
aluminium in the blast furnace,
423
on aluminium in pig iron, 575
Guns, heavy, aluminium bronze for,
507, 508
HALL, CHAS. M., electrolytic
method of,
25, 26
process of,
872-880
heat developed
and disiril)-
uted in the
process of,H84
patents of, 373,
■ 374. 375
process, opera-
tion of, in
France, 362
not antedated
b y Deville,
324
reactions and
efficiency
of the
process
of, 38:;-
386
in the pro-
cess of,
3h4
summary of pro-
cess o f ,
374
voltage required
to decom-
pose the
bath of,
238
Halotrichite, 126
Hampden Emery Co., 47, 48
Hampe, Dr. W., analysis of Cowles
Bros', bronze by,
341
Hampe, Dr. W., experiments of, 290
on electro-depcsition
of aluminium,
316
electrolysis of cry-
olite, 308-372
reactions in
Cowles' process,
344
reduction of alum-
ina b.y carbon,
416.417
Handy, J. O., on the determination
of silicon, 610.611
Hardening aluminium, 452, 453
and annealing aluminium
bronzes, 561
Hardness of aluminium, 61, 62
Hare, Dr., experiments of, 4
Harvey Filley Plating Co., electro-
deposition of aluminium by the, 810
Haurd, Jas. S , electro-deposition of
aluminium by, 810
Hautefeuille, process of, for making
crystallized aluminium fluoride,
17(). 171
Head-lights, aluminium reflectors for,
479
Heat, calories of, absorbed by acety-
lene, 241
developed and distributed in
Hall's process, 384
by the combination of some
of the elements with chlo-
rine, bromine or iodine, 232
expansion of aluminium by, 77
formula for calculating the, of
combustion of hydrogen
gas, 240
for expressing the, in carbon,
240
for, of formation of carbonic
oxide, 2-10
for, required to decompose
alumina, 239
generated by the combination of
aluminium with the different
elements, 228
given out by elements combining
energetically with oxygen, 229
of the formation of fluorides,
table of the, 234
specific, of aluminium, 77-81
Helbig on aluminium amalgam, 509
Hellot on the base of alum, 2
Helmet, aluminium, 475
Hemelingen, Aluminium and Mag-
nesium Fabrik at, 24
650
INDEX
Hemelingen, works at, 328
Hercules metal, 51b
Hercynite, 115
probable occurrence of, in iron
ore, 429
H^roult-alloy process in tlie United
States, HO, 31
and Kiliani, apparatus of, for
producing pure aluminium, 391
electrolytic process of, 38()-398
current used in ,392
of, useful effect de-
rived from the
current in, 392,
393
patent of, 373
process, cost of aluminium by
the, 397
Hesse, deposits of bauxite in, 41
Heycock and Neville on aluminium-
lead al-
loys,504
-tin al-
loys, 524
Hirzel on aluminium-silver alloys, 521
Hoeveler on aluminium-antimony al-
loys 496
Hoffman on the base of alum, 2
Holbrook, C. T., on aluminium in
pig-iron, 427-429
Hollow-ware, casting of, in alumin-
ium, 447
Horse-shoes, aluminium, 478
Howard and Hill, patent specifica-
tions of, 439
Howe, H. M., on the role of alumin-
ium in wrought-iron castings, 592
Hunt, A. E., on action of sodium chlo-
ride on aluminium,
97
bauxites of Georgia,
Alabama and Ar-
kansas, 45
Dr. T. Sterry, on the produc-
tion of aluminium by Cowles
Bros', process, 331. 332
Hydrated aluminium sulphate, 126,
127
Hydrochloric acid, action of, on alu-
minium, 91, 92
Hydrofluoric acid, heat of formation
of, 234
Hydrogen, action of, on aluminium,
106
carburetted, reduction by, 408-
410
compounds, voltage required to
decompose, 237
Hydrogen, electro-chemical equiva-
lent of, 301
gas, equation for the temperature
at which alumina will be-
gin to be reduced by, 240
formula for calculating the
heat of formation of, 240
reduction by, 405, 407
of alumina, 231, 240
aluminium chlo-
ride, bromide,
and iodide, 233,
234
sulphide and sulphur, action of,
on aluminium, 86, 87
reaction with, of neutral so-
lutions of aluminium salts,
111
union of, with oxygen to form
water, 226, 227
ILLINOIS Pure Aluminium Co.,
manufacture of culinary utensils
by the, 485
India, corundum in, 47
Instruments, astronomical and philo-
sophical, use of aluminium
bronze for, 567
surgical, 480
Iodide of aluminium, 118
Iodine, action of, on aluminium, 106
Ireland, deposits of bauxite in, 41
Iron aluminate, 115
-aluminium alloys, Brin Bros',
process of pre-
paring, 425
Cleaver's patent
for producing,
424, 425
Faraday and Stod-
art's investiga-
tions on, 422,423
preparation of, by
an alumin-
ium com-
p a n y in
Kentucky,
425, 426
of, by the Alu-
minium Pro-
cess Co. ,426,
427
and aluminium, alloys of, 572-
605
(and aluminium), determination
of, in aluminium, 611-614
blast furnace, reduction of alu-
minium in the, 429
INDEX,
651
Iron, Castner's process of removing,
from aluniiuium-sodium chlo-
ride, 163
commercial, aluminium taken up
by, 574, 575
composition of, used in testing
the efifects of ferro- aluminium,
597
determination of aluminium in,
H21 , 622, 623
of, in aluminium bronze, 624
of, modification of Deville's
method, 612-614
does the aluminium remain in
castings of? 5il8, 599
effect on grain of, by the addition
of ferroaluminium, 601 ,(i()2
of, on the malleability of alu-
minium, 75
melting point of alu-
minium, 66
elimination of, from aluminium,
449
increase in elasticity of, bv the
addition of ferro-
aluminium, 6(10. COl
fluidity of by ferro-
aluminium, 602
hardness of, by alu-
minium, 603
transverse strength
of, b)' the addition
of ferro-aluminium,
599, 600
influence of, on aluminium, 572
the melting point
of aluniin
ium, 572. 578
poor, practical benefit to, from
ferro-aluminium, 603, 604
practical results of adding ferro-
aluminium to, 605. 606
puddling, influence of aluminium
in, 594, 595
qualitative test for, 606
reduction by and in presence of,
41H-429
in the shrinkage of, by ferro-
aluminium, 602. C03
of aluminium sulphide by, 236
r61e of, in aluminium, 53
salts, voltage required to decom-
pose, 237
wrought, effect of aluminium on,
581-595
explanation of the increased
fluidity of. by the addition
of aluminium, 589, 590
Ivins, E., process of, for making me-
tallic tubes, 454
TABLOCHOFP, P., apparatus of,
J for decomposing .sodium or po-
tassium chlorides, 219
Jacquemont, M., 15
Jarvis, G. A., improvement in the
manufacture of sodium patented
by, 203
Javel, methods used by Deville at,
252-257
Jeangon, J. A., process of, for depos-
iting aluminium, 309, 310
Jewelry, use of aluminium for, 601,
502
Johannes, I. H., alloy of, 504
Joule on the amalgamation of alu-
minium, 507
Julien, Capt., tests by, of aluminium-
copper alloys, 537
Juniata Valley, manufacture of alu-
minous pig-iron from the iron ores
of the, 428
KAGENBUSCH'S process, 325, 326
Kalait, 131
Kamarsch, test of aluminium wire
by, 70
Kaolin, 48, 49
composition of, 48
deposits of, 49
formation of, 48
properties of, 48, 49
value of, 49
Karsten, experiments of, 4
on woolz steel, 576
Keep, J. W., investigations of, on the
effect of ferro-alumin-
ium, 597, 5fl8
on effect on the grain of
iron by the addition
of ferro-aluminium,
601,602
t)n increase in the fluid-
ity of iron by ferro-
aluminium, 602
on shrinkage of alu-
minized cast-iron, 602,
603
tests by, 599
of the solidity
of castings, 5^7
Kentucky, aluminium company in,
403
preparation of iron-aluminium
alloys by an aluminium com-
pany in, 425, 426
652
INDEX.
Kerl and S'.ohman on engraving alu-
minium, 45(5
Kettles, steam, of aluminium, 486
Kiliani, Dr., modifications in Her-
oult's process by, SO
Klaproth, experiments of, 4
Kleiner, Dr. B-, process of, 25, 347-
853
electrical
power con-
sumed in,
352
purity of the
aluminium
prod need
by, 352,353
trial of process of, at
Neuhausen, 38 S
Knife, use of, in testing the quality
of aluminium, 62
Knives, aluminiurn, 486
Kuowles, patent of, -110
Kopp on the specific heat of alumin-
ium, 78
Kosman,Dr., on reactions in Castner's
process,
215-217
Cowles '
process,
344
Krauchkoll on aluminium amalgam,
509
Krupp's works, apparatus erected at,
293, 294
LACE, aluminium in, 475
La Glaci^re, improvements in
the manufacture of sodium at,
197-199
Lamps, safety, of aluminium, 479
Land, C. H., process of, for soldering
aluminium, 465
Laugley, Prof. J. W., on aluminium-
chromium
- alloys, 499
expaii si on
of alumin-
i u m b y
heat, 77
specific
gravity of
alumin-
ium, 64
Latent heat of fusion of aluminium,
79, 81)
Laur, F., on French bauxites, 44
process of, for calcining
bauxite, 143
Lauterborn, F., decomposition of alu-
minium sulphide by
antimony and car-
bon proposed by,
438
on reduction of alu-
minium sulphide by
iron, 418
patent of, 433, 434
for preparing
aluminium
sulphide,
178
Lavoisier on alumina, 3, 4
Lead and aluminium, alloys of, 503,
504
cupellatiou of aluminium with,
450
determination of, in aluminium,
614
bronze,
624
oxide, action of aluminium on,
105
qualitative test for, 606
reduction by, 435, 436
separation of, from aluminium,
449
solutions, action of aluminium
on, 101, 102
Leaf, aluminium, 76
beating and tempering of,
451:
LebedefF, process of, 409
Le Chatellier, method of, for reduc-
ing aluminium com-
pounds, 324, 325
on tensile strength of
annealed aluminium
wire, 73
test by, of resistance
of annealed alumin-
ium bronze, 560
tests by, of tensile
strength of alumin-
ium bronzes, 555
Lechesne, 515
Ledebuhr on aluminium-iron alloys,
574
Lejeal, on aluminium-chromium al-
loys, 5(10
-cobalt alloys, 500
-lead alloys, 504
-nickel alloys, 511
-titanium alloys, 526
Le Roy, G. A., tests by, of the action
of .svilphuric acid on aluminium, 89
Lessiveur methodique, 146
INDEX.
653
Le Verrier, determinations by, of the
melting points of alu-
minium bronzes, .'548
on carbon in commercial
aluminium, 57, 58
on diminishing the
amount of silicon in
aluminium, 45:^
on evolution of gas by
molten iron, 593
on nitrogen in commercial
aluminium, 58, 59
on specific heat of alu-
minium, 78
process of preparing alu-
minium carbide by, 124
study by, of the melting
points of aluminium-
copper alloys, 634, 535
tests by, of aluminium-ti-
tanium al-
loys, 526,
-tun g s t e n
alloys, 527
Levy, I/., on aluminium-titanium al-
loys, .'26
Lieber, R., process of, for preparing
alumina, 141, 142
Light, obtaining of, by burning alu-
minium, 490
Lime-kiln for furnishing carbon di-
oxide, 147
phosphate of, action of, on alu-
minium, 106
water, actionof,on aluminium,100
Lisle, Dr., analysis of native alum
by, 50, 51
experiments of, 409, 416
in reducing
alumin-
ium sul-
phide by
zinc, 485
on reduc-
tion o f
alumin-
ium com-
po u n d s
by tin,
439, 440
on removal
o f zinc
from alu-
minium,
450
on electro-deposition of
aluminium, 316
Lithographic plates, use of aluminium
for, 488, 489
Lockport. description of Cowles Bros',
process as carried on at, 333-
339
Hall's experiments at, 376
Locomotive head lights, aluminium
reflectors for, 479
Lorenz, L., on the thermal conduc-
tivity of aluminium, 82
Lossier, method of, 353, 354
Low carbon steel, aluminium for, 578
Lowig, experiments of, in precipitat-
ing solution of sodium aluminate,
143
Lubbert and Roscher, investigations
of, on the action of organic acids on
aluminium, 93, 94
Lunge, Prof. G., tests by, of the action
of organic acids upon aluminium,
94-96
MABERY, Prof. C. F., 28
ona peculiar
product
formed in
the electric
furnace, 499
on prodjc-
tion of alu-
minium l)y
C o w 1 e s
Bros', pro-
cess, 3l9-
331
process o f
m.aking al-
umi n i u m
ch 1 o r i d e
patented
by, 165
MacKellar, T., type-metal of, 504
Macquer on the earth of alum, 3
Mac Tear, F., on Castner's sodium
process, 207-212
Magnesia, heat developed in the re-
action of, on aluminium chloride,
233
Magnesite, calcined, for lining cruci-
bles, 444, 445
Magnesium, action of, on aluminium
fluoride, 235
aluminate, 115
and aluminium, alloys of, 504^,505
reduction by, 437, 438
of alumina, 229, 230
of aluminium sulphide by,
236
654
INDEX.
Magnesium salts, voltage required to
decompose, 238
und Aluminium Fabrik, direc-
tions bj', for preparing alumin-
ium bronzes, 646, 547
Magnetism of aluminium, 67
Malleability of aluminium, 75, 76
influence of sili-
con on the,
518
Mallet on action of caustic alkalies on
aluminium, 99
color of aluminium, 59
elasticity of aluminium, 69
fusibility of aluminium, 65
malleability of aluminium,
75
specific gravity of alumin-
ium, 62
heat of aluminium, 77.
78
production of aluminium nitride
by, 125
Manganese and aluminium, alloysof,
505, 506
anal y sis of alloys
of, 626
determination of, in aluminium
bronze, 625
dioxide, action of aluminium on,
105
heat developed in the reaction of,
on aluminium chloride, 233
oxide, action of aluminium on,
436
pure metallic, method of produc-
ing, 105, 106
production of, 436
reduction by, 436
of aluminium sulphide by,
236
salts, voltage required to decom-
pose, 237 !
Mann, A., patent of, 417
Mannesmann, addition of tungsten to
aluminium recom-
mended by, 527
process of cold rolling,
454
Marggraff on alum and. its earth, 2
Margottet, M., description by, of ap-
paratus for the prep-
aration ofaluminium
chloride, 157-159 j
on action of alumin- '
ium on solutions of I
metallic chlorides, !
102
Margottet, M., on action of hydrogen
sulphide on aluminium, 87
Marshall Furnace, Penna., aluminium
in pig iron produced at the, 428
Mat on aluminium, 456
Medicine, use of aluminium in, 480.
481
Melting aluminium, 442-445
point of aluminium, 66
points of aluminium-copper al-
loys, 5:-i5
-tin alloys, 525
Meuge, patent of, 347
Mercurous chloride, action of alu-
minium on, 106
Mercury and aluminium, alloys of,
506-509
bottles, manufacture of sodium
in, 185-190
solutions, action of aluminium
on, 101
Metal, electro deposition of a, 304,305
mitis, analyses of, 584, 585
method of treatmentof,585,586
quality of the, produced by
Minet's process, 361
requirements of a, for coinage,
483, 484
Metallic chlorides, anhydrous, prepa-
ration of, 165, 166
solutions of, action of
aluminium on, 102
oxides, action of aluminium on,
105, 106
salts, action of solutions of, on
aluminium, 100-102
Metals, alkaline, reduction of, theo-
retically considered, 237
coaling of, with aluminium, 307,
308, 469-472
effect of a small quantity of alu-
minium on, 494, 495
heat developed by, in forming
chlorides, 232, 233
influence of aluminium on the
color of, 494
other, comparison of production
of, with aluminium, 38
order pf the aflinity of the, for
sulphur, 236
various, prices of, 61. 65
relative electrical resistances
of, 82
weights of, to give a cer-
tain strength, 74, 75
specific gravity of, 64
heat of aluminium com-
pared with, 81
INDEX.
65S
Metals, veneering of, with aluminium,
473
Meudon, tests of aluminium-copper
alloys at, 587
Michel on aluminium-iron alloys, 573
-manganese alloys, 505
-nickel alloys, 510
-titanium alloys, 526
-tungsten alloys, 527
Mierzinski, Dr. S. , on the electro-depo-
silion of alumin-
ium, 316
on the use of the
electric furnace,
27,28
" Mignon," the, 476, 477
Military uses of aluminium, 475, 476
Milk, action of, on aluminium, 94
Miller, C. B., anti-friction alloy of, 504
Milling screens, 567
Milton, England, aluminium works
at, 840
Milwaukee, the American Aluminium
Company of, 365
Minargent, 511,512
Mine work, use of aluminium for,
479, 4)-0
Mineral soda, 276
Minet, A. , electrolytic process of, 354-
362
of, composi-
tion and
properties
of the
baths used
in the,
357, 358
of, disposi-
tion of the
apparatus
in the,
355-357
experiments of, 26
installations of the process
of, 361, 362
on aluminium-tin alloys,
5-24. 525
on silicon in aluminium, 51:-'
on strength of aluminium
strongly worked and an-
nealed, 74
results of the experiments
of, 359-361
test by, of an aluminium-
tin alloy, 523
views of, 358, 359
voltage required to decom-
pose the bath of, 239
Mitis castings, absence of aluminium
in, 587
history of, 582, 583
mixture for, 584
Nobel's furnace for, 585, 586
production of, 583
properties of, 586, 587
rationale of the process of
making, 587-594
raw material for, 583-585
strength of, 587
metal, analyses of, 584, 585
method of treatment of, 585,
586
Molybdenum and aluminium, alloys
of, 509, 510
Monckton's patent for reducing alu-
minium compounds, 325
Monnier, M. A., early manufacture
of sodium by, 17
Montgelas, R. de, patent of, 437
patents of, for the
electrolysis o f
aqueous s o 1 u -
tions, 312, 313
process patented
by, for producing
aluminium chlo-
ride and the
double chloride
with sodium, 164
Montucci,H., alviminium coinage pro-
posed by, 483
Morin, arguments of, that aluminium
bronzes are true chemical com-
binations, 541, 542
on anti-friction qualities of alu-
minium bronzes, 563
on veneering aluminium with
silver, 473
Morris, J., claim of, 405, 406
Moulds for casting aluminium, 447
Mourey, M., alloys used by, for sol-
dering aluminium, 461 ,
462
, solders of, for alumin-
ium, 459-461
Muller, H., process of, for preparing
alumina, 142
NACCARI on the specific heat of
aluminium, 7H
Nanterre, composition of the mix-
tures used at, 258, 261
furnace used at, 261
improvement in the manu-
facture of sodium used
at, 199-201
656
INDEX
Nanterre, process for utilizing alu-
minous fluoride slags
used at, ]4«, 149
rationale of the process
used at, 257
works at, lo
Napoleon III., assistance of, 11, 12
interest of, in alumin-
ium, 475
Nelson, recommendation by, 473
Neogen, 512
Nelto, Dr. C, patents of, 31
process of, 290-294
for the pro-
duction of
sodium,
217-219
and Saloman, processes of, 31
Neuhausen aluminium bronzes, test
of, 558. 553
tests at, of the suitability
of aluininiuui bronze
for boats, 506
works at, 29, 388
manufacturing cost
of aluminium at
the, 397. 398
selling price of alu-
minium at the, 397
New Ken.sington, Pa., aluminium
works at, 382 •
New Mexico, deposit of native alum
in, 50
Newport,Ky., aluminium works in, 403
Niagara Fal ls,alumi nium works at, 382
Nickel andaluminium, alloys, 510.51 1
analy sis
of, 626
use of alloy of, on
the "Defender,"
478
bronzes containing, 512-515
copper and aluminium, alloys of,
511-516
determination of, in aluminium
bronze, 625
plating aluminium with, 473
salts, voltage required to decom-
pose, 237
Nicolai and Langenbach, process of,
for soldering aluminium, 466
Niewerth, H., patent of, 418, 419
process of, 411-413
for the re-
duction of
alumin-
ium com-
pounds, 268
Nitrate of aluminium, 130
Nitre, action of, on aluminium, 104
purification of aluminium by, 449
Nitric acid, action of, on aluminium,
90, 91
cold, amount of the action
of, on aluminium, 90, 91
resistance of aluminium to,
488
Nitrogen and aluminium, compounds
of, 125
effect of, on aluminium, 58. 59
presence of, in commercial alu-
minium, 58. 59
Nobel's furnace for mitis castings,
585, 586
Novel, J., alloys for soldering recom-
mended by, 464, 466
Niirnberg gold, 501
ODOR of aluminium, 66, 67
Oersted, experiments of, 6
in reduc-
ing alu-
minium
c o m -
pounds,
246-247
Ohio, native alum in, 50
Oil, action of, on aluminium, 94
Oldbury, England, aluminium works
at, 28, 212-215, 270, l71
mode of conducting the
reduction at, 271, 272
Omholt, I., furnace of, 354
Opera glas.ses, aluminium, 481
Organic acids, action of, on alumin-
ium, 92-97
secretions, action of, on alumin-
ium, 98, 99
Osmond, Mr., on the melting point
of aluminium-iron alloys, 588
Ostberg, Mr., explanation by, of the
rationale of the pro-
cess of making mitis
castings, 587
on manufacture of
ferro-aluminium, 425
on strength of mitis
castings, 587
Overbeck and Niewerth, process of,
for depositing aluminium, 311, 312
Overheating of aluminium, 452
Oxides, metallic, action of aluminium
on, 105, 106
Oxygen, heat given out by elements
combining energetically with,
229
INDEX.
657
Osygen, union of hydrogen with, to
form water, 226, 227
PACHNOWTE, 121
Painting, protection of aluminium
boats by, 478
Pans, evaporating, use of aluminium
for, 485
Paracelsus, separation of alum and
vitriols by, 2
Paraluminite, 127 J
Paris Exposition, 1889, aluminium 1
industry at the, 33 |
Parke's process, addition of alumin-
ium to the zinc used in, 529, 530
Passaic Art Casting Co., Passaic, N. J.,
castings in aluminium made by
the, 446, 447
Passementerie of aluminium, 76, 475
Patricoft, England, works at, 382
Pearson and Pratt, patent of, for the
reduction of aluminium in the
iron blast furnace, 420
Ividdon and Pratt, patent of, 404 :
Turner and Andrews, claim of, i
413 I
Peligot, cupel] ation of aluminium by, 1
450 i
Pennsylvania Salt Company, purity of j
cryolite from
the, 367
use of cryolite
by the, 45, 46
Percy, Dr., experiments of , 17
on aluminium bronze, 538
in pig iron, 575
and Dick, experiments of, 283-
285
Periodic classification of the ele-
ments, position of aluminium in
the, 107, 108
Perspiration, action of, on alumin-
ium, 98
Peters, Mr., on the analysis of ferro-
aluminiums, 619
Petitjean on preparation of a double
sulphide of aluminium
and sodium, 177
process of, 408, 409
Petroleum furnace for mitis castings,
585
Philadelphia Public Buildings, coat-
ing the iron work of the tower of '
the, with aluminium, 316, 317
Phosphate of lime, action of, on alu-
minium, 106
Phosphates of aluminium, 130
Phosphor-aluminium bronze, 571
42
Phosphorus and aluminium, alloys of,
516,517
chloride of, 117,
118
reduction by, 440, 441
Pickling and cleaning aluminium, 456
Pieper; process for preparing artificial
cryolite patented by, 170
Pig iron, presence of aluminium in,
574, 575
irons, aluminium in, 423, 427-429
Pionchon on the specific heat of alu-
minium, 79
Pittsburgh Reduction Co., 26
aluminium-
nickel
alloys
of the,
511
-titanium
alloys
ma de
by the,
526
cost of pro-
ducing al-
umini u m
bythe,381
enlargement
and re-
moval of
the plant
of the,
381, 382
mechanical
tests of al-
umini u m
by the,
70-72
mode of pol-
i s h i n g
sheet alu-
minium
used by
the, 456
organization
and plant
of, 376
remelting
plant of,
379
suit of the,
against
the Cowles
Co., 346,
347
Testing Laboratory, analyses of
commercial aluminium by the,55
6s8
INDEX.
Plants, alumina in, 39, 40
Plates, aluminium, 486
Plating on aluminium, 472, 473
Platinum, plating of, on aluminium,
473
Polishing, burnishing and grinding
aluminium, 455, 456
Pontoons, aluminium, 476
Potash alum, 128
Potassium aluminate, 114
and sodium, Netto's patents for
the reduction of, 31
reduction of aluminium
compounds by means
of, 246-300
chloride, apparatus for decom-
posing, 219
dangers of handling, 181
heat developed in the reaction of,
on aluminium chloride, 233
reduction of aluminium sulphide
by, 236
salts, voltage required to decom-
pose, 237
Pott on the base of alum, 2
Pressing of aluminium ware, 455
Pressure, influence of, on aluminium
powder, 66
Proctor, B. S., on the resistance to
corrosion of aluminium bronzes,
•564, 565
Propeller blades, aluminium bronze
for, 568, 569
Puddling, influence of aluminium in,
594
Pumps, use of aluminium bronze for,
567
Purification of aluminium, 447-452
Purple alloy of aluminium and gold,
502
ore, use of, in Castner's sodium
process, 208
/QUARTZ, occurrence of, in cryolite,
"70
y
RAILWAY carriage, aluminium, !
478 :
Rammelsberg, Prof., investigations '
by, of the dif- i
f erent states 1
of silicon in
aluminium, 5H i
on the forms in
which silicon i
occurs in alu-
minium, 609
Reactions, chemical, of aluminium
salts. 111
in the Hall process, 384
Reagents, ordinary, impossibility of
the reduction of alumina by,
230
reaction with, of neutral solutions
of aluminium salts, 111
Reduction by double reaction, 411-
413
furnace, 266
of alumina by acetylene gas, 241
aluminium chloride or alumin-
ium-sodium chloride,
methods based on the,
246-800
compounds by electric-
ity, 236
by other means than
sodium or electric-
ity, 402-441
theoretically consid-
ered, 226-245
cryolite, methods based on
the, 274-300
Reflectors, use of aluminium for, 479
Regelsberger, F., on the determina-
tion of silicon, 610
Regnault on the specific heat of alu-
minium, 77, 78
Reichel on preparation of alumin-
ium sulphide, 176
reduction of aluminium
sulphide
b y cop-
per, 417
by iron,
418
Reillon, Montague and Bourgerel, pat-
ent of, 409
process for
producing
alumin-
ium sul-
phide pat-
ented by,
177
Reimar, G. W., statement by, 403
Reinbold, H., recipe of, for deposit-
ing aluminium, 312
Republic Mining and Manufacturing
Co., 41
Rheinfelden, projected aluminium
works at, 395
Rhine Falls, plant at the, 388, 394.
3;v5
Ricciardi on the assimilation of alu-
mina by plants, 39, 40
INDEX.
659
Richards, J., alloy of, as an addition
t o . t h e galvanizing
baa, 529
bronze invented by, oR3
on an aluminium-tin al-
loy, 523, 524
on bufl&ng and burnish-
ing aluminium, 456,456
solder of, for aluminium,
467-469
Rifle, aluminium bronze, test of an,
566, 567
Riley, E. , analyses by, of mitis metal,
584, 585
Roberts- Austen, Prof. W. C, on alu-
minium-gold alloys, 501 , 502
Rocca, manufacture of alum in, 1
Roche on aluminium-antimony al-
loys, 496
Rock alum, 1
Rogers, Prof., analysis of pure cryo-
lite by, 46
experiments of, in re-
ducing sodium com-
pounds, 219-222
on wootz steel, 576
process of, H65-368
Rolling aluminium, 453, 454
Roman, B. I., solder of, for alumin-
ium, 466, 467
Roscoe, Sir H., on the sodium works
at Oldbury, 212-215
Rose, H., experiments of, 17
in the reduc-
tion of alu-
minium
compounds,
274r-283
Rossiter & Co., aluminium boats con-
structed by, 478
Rossler, patent of, 530
Rouen, history of the works at, 14
Roussin on the precipitation of alu-
minium by magnesium, 437
Rowing shells, aluminium, 478
Royal Gun Foundry, Woolwich, tests
of aluminium bronzes in the, 554,
555, 556
Rupp, tests by, of food kept in alu-
minium vessels, 94
Ruprecht and Tondi, experiments
of, 4
PAARBURGER,
letter of, on the
Gratzel process,
328
process, 24, 25
Safety-lamps, aluminium, 479
Saint-Michel, Savoy, installation of
Minet's pro-
cess at, 362
works at, 26
Salindres, apparatus for preparing al-
uminium chloride at,.
157-159
expense of the process in:
use at, 267, 268
preparation of alumina at,
137-141
principal chemical reac-
tions in the process used
at, 265
process in use at, 264-268
works at, 15
Saliva, action of, on aluminium, 94
Saloman and Netto, processes of, 31
Salt, common, reaction of, on baux-
ite, 142
Salts, basic, of aluminium, 110
metallic, action of solutions of,
on aluminium, 100-102
neutral, of aluminium, 110
Saner, C, process of, for soldering
aluminium, 464
Sauerwein, process of, for the decom-
position of cryolite, 150, 151
Sauvage, F. H., alloy of, 512
Savaresi, experiments of, 4
Savoy, installation of Minet's pro-
cess in, 362
Scales, aluminium, 482
Schaffhausen, aluminium works near,
388 _
Schering, use of Gratzel's process
by, 328
Schlosser, directions by, for soldering
for aluminium bronze,
569, 570
solder for aluminium re-
commended by, 462, 463
Schmidt, Dr. O., on the electrolysis
of cryolite, 368, 369
Schuch, decomposition of cryolite ac-
cording to, 151, 152
Schulze, Fr., test of, 608
Scientific instruments, use of alumin-
ium for, 481-483
Sea-water, action of, on aluminium,
97, 98
Secretions, organic, action of, on alu-
minium, 98, 99
Sel alumineux, 2
Selenide of aluminium, 1 22
Selenites of aluminium, 129
Selenium andaluminium, alloys of, 519
chloride of, 117
66o
INDEX.
Self, E. D., test by, of aluminium
bronzes, 657, 558
Sellers, Mr., experiments of, on the
use of aluminium with iron in
casting, 595
Sellon, J. S., process of, for soldering
aluminium, 464
Senet, M. L., process of, for deposit-
ing aluminium, 311
Sestini, on the solution of alumina in
carbonated waters, 131
Sevrard, M., process of, for plating
aluminium on copper and brass,
469, 470
Sextant, aluminium, 481, 482
Seymour, F. J., patent of, 432, 433
Shaw, Thos. , phosphor-aluminium
bronze of, 571
Sheet-iron, coating of, with alumin-
ium, 471, 472
Shimer, P. W., on the occurrence of
spinel in blast-furnace slags, 115
Ships, use of aluminium for, 97, 98
Siderite, occurrence of, in cryolite, 149
Siemens, Sir W. , electric furnace of, 27
-Martin steel, basic, effect of alu-
minium on, 578
Silicates and borates, action of, on
aluminium, 103, 104
of alumina, extraction of alumina
from, 142
of aluminium, constitution and
properties of, 132
Silicon-aluminium bronze, 570, 571
and aluminium, alloys of, 517-519
bronze, Evrard's process for pro-
ducing, 414
condition of the, in aluminium, 56
determination of, in aluminium,
608-611
bronze,
624_
different states of, in aluminium,
56
diminishing the amount of, in al-
uminium, 452
double role of, in aluminium,
518, 519
effect of, on aluminium, 518
malleability of alu-
minium, 75
melting point of al-
uminium, 66
elimination of, from aluminium,
449
experiments on aluminium con-
taining, 450, 451
graphitoidal, 56
Silicon, reduction by, 441
r&le of, in aluminium, 53
Silliman, Prof. Benj., experiments
of, 6
Silver and aluminium, alloys of, 519-
521 _
analysis of alloys of,
626
chloride, decomposition of, by
aluminium, 106
sub-chloride, bromide and
iodide of, as a flux in sol-
dering aluminium, 466
determination of, in aluminium,
615
plating aluminium with, 473
qualitative test for, 606
salts, voltage required to decom-
pose, 237
solutions, action of aluminium
on, 101
sulphide, decomposition of, by
aluminium, 87
veneering aluminium with, 473
Silvering aluminium, 472
Slag, freeing aluminium from, 447,
448
or flux, influence of, on the al-
uminium, 253
Slags, blast-furnace, occurrence of
spinel in, 115
composition of, 262, 263
formed in producing bronze, anal-
ysis of, 342, 343
f erro- aluminium,
analysis of, 342
utilization of aluminous, 148
Smith, Dr., patents of, 432
Smith, Prof. E. F., method of, for de-
termining aluminium in iron anfl
steel, 62v;, 623
Soci^t^ Anonyme La F?rro-Nickel,
aluminium-nickel-copper alloy
made by the, 515
Electro-Metallurgique Franjaise,
30
works of
the,395,
396
Metallurgique Suisse', 29
plant of the,
388-390
Soda alum, 129
mineral, 45
Sodium, advantages of, over potas-
sium, 181
aluminate, 114
precipitation of, 143
INDEX.
66 1
Sodium-aluminium chloride, 117
analyses of the residues from the
production of, 210
and aluminium, alloys of, 521
chloride, reduction of, by
~ zinc, 429
manufacture of chloride
of, 152-168
sulphide of, 1 11
potassium, Netto's patents
for the reduction of, 31
reduction of aluminium
compounds by means
of, 246-300
apparatus for condensing, 180
reducing, condens-
ing and heating
in the manufac-
ture of, 186
carbonate, separation of, from
alumina, 148
cast-iron vessels for producing,
199
Castner's process of manufactur-
ing, 203-217
chloride, action of, on alumin-
ium, 97, 98
apparatus for decomposing,
219
calories required for the de-
composition of, 369
molten, electrolysis of, 222,
223
composition of mixtures used in
the manufacture of, 182-184,194
compounds, reduction of, by elec-
tricity, 219-225
continuous manufacture of; in
cylinders, 190-194
cost of, 22, 201
by Castner's process, 210
crucibles used in the production
of, 208
determination of, in aluminium,
615, 616
Devilie's improvements in the
manufacture of, 180-194,
197-201
methods of reducing alumin-
ium chloride by, 252-257
early manufacture of, in the
United States, 17
first patent granted in the United
States on the manufacture of,
204
fluoride, injury to crucibles by,
263
furnace for the production of, 208
Sodium furnaces, experiments of Tis-
sier Brothers on, 13
heat developed in the reaction of,
on aluminium chloride, 233
evolved in action of, on alu-
minium fluoride, 235
history of, from Davy to Deville,
179, 180
manufacture of, 179-225
in mercury bottles,
185-190
method employed in the manu-
facture of, 182
minor improvements in the man-
ufacture of, 201-203
patents, Castner's, 23
perfection in the process of pro-
ducing, 10, 11
phosphate, reactions with, of
neutral solutions of aluminium
salts. 111
process, radical change in the, 22
processes, Cunningham's, 291,292
production of, by Netto's process,
217-219
properties of, 181, 182
quantity of metal reduced by, 258
reactions in the production of,
207, 215-217
reduction by, of aluminium fluo-
ride, 294-300
of aluminium compounds by
other means than,
402-441
-sodium chloride by,
265-268
sulphide by, 236
salts, voltage required to decom-
pose, 237
solid, reduction by, 253-256
substitutes for, in reducing alu-
minium, 234
sulphate of, use of, in decompos-
ing bauxite, 143
Tissier Bros', method of manu-
facturing, 194-197
use of, in melting aluminium, 452
mixtures employed in the
manufacture of, 184, 185
vapor, reduction by, 256, 257
yield of, in Castner's process, 210
Solder, Richards', for aluminium,
467-469
Roman's, for aluminium, 466, 467
Sauer's, for aluminium, 464
satisfactory, requirements of a,
457
Sellon's, for aluminium, 464
662
INDEX.
Solder, Thowless', for aluminium, 463,
464
Solders, Frishtauth's, for aluminium,
462
Mourey's, for aluminium, 459-461
Schlosser's, for aluminium, 462,
463
Soldering aluminium, 457-469
bronze, 569, 570
Solutions of aluminium salts, reac-
tions of reagents upon, ] 1 1
Sound, velocity of, in aluminium, 69
Sounding boards of aluminium, 68, 69
South Carolina, kaolin in, 49
Southern Bauxite and Mining Co., 41
Specific gravity of aluminium, 62-65
molten aluminium,
386
test, 607, 608
Spencer, J. W. , tests by, of the effect
of aluminitim on crucible steel,
580, 581
Spiegeleisen, action of cryolite on, 436
Spilsbury, Mr., test of strength of al-
uminium wire by, 70
Spinel, 115
Spinning and stamping aluminium,
455
Spoons, aluminium, 486
Sprague on the electro-deposition of
aluminium, 315
Springer, Dr. A., on the use of alu-
minium for sounding boards, 68. ()9
Spring on compressing aluminium
powder, 66
Stahl on the base of alum, 2
Stamping and spinning aluminium,
455
Statistics of the aluminium industry,
34-38
Statuettes, aluminium, 519
Stead, J. E., method of, for determin-
ing aluminium in iron and steel,
623
Steel, aluminium, 581
taken up by, 574. 575
Bombay wootz, 422, 576
cast, addition of alumina in the
manufacture of, 423
casters, general use of aluminium
by, 577, 578
castings, use of ferro-aluminium
in making, 577
chrome, aluminium in, 423
determination of aluminium in,
621, 622, 623
high carbon, poor results by add-
ing aluminium to, 579
Steel, soft, effect of aluminium on the
welding capability of, 579
substitution of aluminium for, 487
Stills, use of aluminium for, 485
Stocker on the occurrence of metallic
aluminium, 39
Stoke-on-Trent, works at, 28, 340
Stone-ware, coating of, with alumin-
ium, 471
Strange, Mr., on the use of alumiu-
ivim bronze for astronomical and
philosophical instruments, 567
Strength, tensile and compressive of
aluminium, 70-75
Strontium salts, voltage required to
decompose, 237
Structure of aluminium compounds,
108-110
Stutzer, Prof. A., on the action of
caustic alkalies on aluminium, 100
Styria, deposits of bauxite in, 41
Sulkies, racing, use of aluminium
for, 478
Sulphate, native, of alumina, 50, 51
Sulphates, alkaline, action of, on al-
uminium, 104
double, of aluminium and other
metals, 129
of aluminium, 126, 127
Sulphide of aluminium, 121
reduction of, theo-
retically consid-
ered, 236
Sulphides, voltage required to de-
compose, 238
Sulphur and aluminium, chloride of,
117, 118
hydrogen sulphide, action
of, on aluminium 86, 37
heat developed by combining
with other elements, 235
order of the af&nity of the metals
for, 236
Sulphuretted hydrogen, action of, on
alumin-
ium, 86,
87
of, on so-
lutions
of alu-
minium
salts ,
111
gen eration of, from
aluminium sul-
phide, 121
Sulphuric acid, action of, on alumin-
ium, 88-90
INDEX.
663
Surgery, use of aluminium in, 98, 480
Surveying instruments of aluminium,
4S2
Suture-wire, aluminium, 480
Sweden, rise of the mitis process in,
577 ^
Swiss Metallurgic Co., 29
Switzerland, aluminium works in, 388
amount of aluminium produced
in, 3(5
n^'ABLE ware, use of aluminium for,
1 486. 487
Tacony Metal Co., Philadelphia, ope-
ration of the
electric plant
of the, 316-
318
works of the,
316
Tarnish on polished aluminium, 98
Taste of aluminium, 67
Taylor, W. J., article by, 17, 18
Tea, action of, on aluminium, 95, 96
-kettles, 447
Tellurium and aluminium, allo5-s of,
521,522
Temperature at which acetylene re-
duces alumina,
241
carbon reduces
alumina, 240
hydrogen reduces
alumina, 240
Terre argilleuse, 2
Tests, compressive, of aluminium, 72
mechanical, of aluminium, 70-72
tensile, of aluminium, 71
transverse, of aluminium, 72
Tetmayer, Prof, test by, of alumin-
ium brasses, 532
tests by, of alumin-
ium bronzes, 559
Thenard, M., recommendation by, 9, j
10
Thermal chemistry, reduction of alu- j
minium compounds from the
standpoint of, 226-245
conductivity of aluminium, 82
Thomas and Tilly, patent of. for coat-
ing metals with aluminium, 307,
308
Thompson and White, improvements
by, in the
manufacture
of sodium,
202, 203
patent, 290
Thompson, J. B., process of, for depos-
iting aluminium, 308
R. T., on the analysis of
ferro - aluminiums, 619,
620
W. P., discovery by, of
corundum in the
United States, 47
on the production
of aluminium by
Cowles Bros',
process, 333-339
patent of, 419, 420
Thomson, G. W., on the influence of
aluminium in puddling
iron, 594, 595
J., process of, for preparing
alumina from cryolite by
the dry way, 144-147
Thonichte erde, 2
Thowless, O. M., process of, for man-
ufacturing sodi-
um, 203
proposition of, 403,
404
solder of, for alu-
minium, 463, 464
Thurston, Prof., on the drawing ca-
pacity of aluminium, 454
Tiers Argent, 520, 521
Tilghman, method of, for preparing
alumina, 135, 136
Tin and aluminium, alloys of, 522-525
analysis of alloys of, 626
determination of, in aluminium,
615
bronze,
624
' foil, effect of a small addition of
aluminium on, 524
properties imparted to, by alu-
minium, 523
qualitative test for, 607
reduction by, 439, 440
of aluminium sulphide by,
236
use of, in soldering aluminium,
459
Tissier Brothers, controversy be-
tween, and De-
ville, 13, 14
experiments on so-
dium furnaces
by, 13
history by, of the
works at Rouen,
14
method of, 287,288
664
INDEX.
Tissier Brothers, on action of alka-
line s u 1 -
phates and
carbonates
on alumin-
ium, 104
of alumin-
ium on me-
tallic ox-
ides, 105,
306
aluminium-anti-
mony al-
loys, 495
-bismuth al-
loys, 497
bronze, 538,
539
-gold alloys,
501
-iron alloys,
573
-nickel al-
loys, 510
-pi a t i n u m
alloys,517
-tin alloys,
523
amalgamation of
aluminium,
506
application o f
aluminium to
cast-iron, 595
gilding alumin-
ium, 472
the effect of iron
on alumi n - 1
ium, 572
process of, for the
manufacture of
sodium, 194-197
work by, on alu-
minium, 15, 16
Titanic .acid, constancy of, in Ameri- 1
can bauxites, 45
Titanium and aluminium, alloys of,
525-527
determination of, in aluminium,
617
in aluminium, 53
Tomlinson on the specific heat of al-
uminium, 78
Tondi and Ruprecht, experiments
of, 4
Torpedo boat of aluminium, 477
Transit instruments, aluminium, 482
Trusses, aluminium, 480
Tubes, manufacture of, 454
Tungsten and aluminium, alloys of,
527
Tuning forks, aluminium, 67
Turquois, 131
Type metal, MacKellar's, 504
UNIONVILLE Corundum Mines
Co., 48
United States Aluminium Metal Co.,
organization and plant
of, 396
amount of aluminium pro-
duced in the, 37
Army, use of aluminium
in tlae, 476
Co., plant of the, 382, 383
cryolite in the, 46
deposits of bauxite in, 41
early experiments in, 17
first discovery of corundum
in the, 47
patent on the manufac-
ture of sodium granted
in the, 204
! H^roult alloy process in
the, 30, 31
kaoliu in the, 49
manufacture of aluminium
culinary utensils in the,
485
Mitis Co., organization of,
682, 583
production of corundum in
the, 47
Unwin, Prof, test by, of aluminium
bronzes, 557
Uses, miscellaneous, of aluminium,
490
*■
VALENCY of aluminium in its
compounds, 109
Valoirette, use of, to operate Minet's
process, 362
"Vapor of aluminium, color of, 66
Vehicles, use of aluminium for, 478
"Vendenesse," the, 477
Veneering other metals with alumin-
ium, 473
Very, Prof l-<\, on the magnetism of
aluminium, 67
Vessels, use of aluminium in build-
ing, 476
Villeveyrac (HSroult), bauxite from,
44
Vinegar, action of, on aluminium,
92-97
Vitriols and alums, separation of, 2
INDEX.
665
Volatilization of aluminium, 66
Voltage, equation for the, required
to decompose alumina, 239
required for decomposition at
high tempera-
tures, 302, 303
Minet's bath, 360,
361
in Hall's process, 378
H^roult's process,
392
to decompose anhy-
drous molten sub-
stances, 237
WAGNBR, R., improvements by,
in the manufac-
ture of sodium,
201,202
process for prepar-
ing alumina pro-
posed by, 142,
143
Wagons, ammunition, of aluminium,
476
Wahl and Greene, use of aluminium
by, 436
Walker, A., patents of, for the electro-
deposition of aluminium, 313, 314
Wanner, M., claims of, 441
Warren, H., experiments of, 363,
364
reduction by, of alumina
with hydrogen, 407
H. N., boron-aluminium
bronze of, 571
on aluminium-arse-
nic alloys,
497
-boron a 1 -
loys, 498
process for produc-
ing anhydrous me-
tallic chlorides re-
commended b y ,
165, 166
Washington, England, aluminium
■works at, 18
Monument, aluminium tip on
the, 33
Navy Yard, tests of bronzes at
the, 554, 556
Water, action of, on aluminium, 85,
86
electro-motive force required to
decompose, 303
union of hydrogen with oxygen
to form, 226, 227
Watertown Arsenal, tests of Cowles'
bronzes at the, 555, 656, 557
Watt, A., on the electro-deposition of
aluminium, 316
Wavellite, 131
Weber, decomposition of cryolite in
the establishment of, 151
Webster Crown Metal Co., bronzes
containing nickel made by the,
512-515
Mr. , bronzes of, containing nickel,
512-515
inventions of, 21, 22
process of, for preparing alu-
mina, 136,137
Wedding, Mr., on Basset's process
for obtaining aluminium, 431
Wegner and Guhrs, flux in soldering
aluminium re-
commended
by, 466
process of, for
plating a 1 u -
minium, 473
Weights, aluminium, 482
Welding aluminium, 457
Weldon, W., on the prospects of the
aluminium industry,
20, 21
process of, 436
Wellman, aluminium boats in the
expedition of, 478
Werner, E., flux in soldering alu-
minium recommended by, 466
West, Thomas D., on casting alu-
minium bronze, 549-552
Wheelbarrows, aluminium, 487
Wilde, A. E-, invention of, 435, 436
Williams Aluminium Co., New York,
aluminium-
ferro - sili-
con of the,
595
manufac-
ture of al-
uminium-
ferro - sili-
con by,
427
Willson, Mr., process of, 399
Winckler, A., patent of, 399
Dr. C, experiments of, in
reducing a 1 u -
mina by mag-
nesium, 229, 230
on coating metals
with alumin-
ium, 470, 471
666
INDEX.
Winckler, Dr. C, on electro-deposi-
tion of a 1 u -
minium, 315
reduction of alu-
mina by mag-
nesium, 437,
438
retrospect by, of
the art of work-
ing aluminium,
18,19
Wine, action of, on aluminium, 94, 95
Wirtz & Co., aluminium works of, 18
Wittenstroem and Nobel, discovery
by, 582
patent of, for use of aluminium
in casting wrought iron and
steel, 577
Wocheinite, 41
Wohler, F., experiments of, 7, 8
in reduc-
ing alu-
minium
c o m -
pounds,
247-250
modifications by, of re-
ducing cryolite, 289
on aluminium-arsenic al-
lo);s, 497
-calcium alloys,
498, 499
-chromium a 1 -
loys, 499
-magnesium al-
loys, 504, 505
-molybdenum
alloys, 509,510
-phosphorus al-
loys, 516, 517
- s e 1 e nium al-
loys, 519
-tellurium a 1 -
loys, 521, 522
-titanium alloys,
525
process of, for preparing
aluminium chloride,
152
Wootz steel, Bombay, 422, 576
Worcester, Mass., plant for the manu-
facture of mitis castings at, 582
Working aluminium bronzes, 561,
562
in aluminium, 442-491
Wright, Dr. C.R. A.,on aluminium-an-
timony al-
loys, 495,
496
-cadmium
alloys, 498
Wrought iron castings, causes for
blow holes in, 590-592
effect of aluminium on,
581-595
explanation of the in-
creased fluidity of, by
the addition of alumin-
ium, 589, 590
YACHTS, aluminium, 476
Yates, H. N., on the analysis of
ferro-aluminiums, 618, 619
yDZIARSKI, A., patent of, .'^64
/y Zinc aluminate, 115
and aluminium, alloys of, 528-
530
analysis of,
copper and aluminium, alloys
of, 580-533
determination of, in aluminium,
614, 615
bronze,
625
minute
quantities
in alumin-
ium, 626
effect of, on aluminium, 528
industry, use of aluminium in
the, 529, 530
oxide, action of aluminium on,
105
qualitative test for, 606, 607
r e a c tion of, on aluminium
chloride, 235
reduction by or in presence of,
429-435
of aluminium sulphide
by, 236
salts, voltage required to de-
compose, 237
separation of, from aluminium,
450
solutions, action of aluminium
on, 102
use of, in soldering aluminium,
459
JANNEY&STEIIMMETZ
No. 421 CHESTNUT STREET
Philadelphia, Pa.
ALUMINUM
Cable Address: { /-\ | j_ j "ALUMINUM."
Ingots, Sheet, Plates, Foil,
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for
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(1)
THE
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MANUFACTURERS OF
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INGOTS, BARS,
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.tV
^y
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(2)
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Specially adapted for castings of great strength and rigidity.
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Equal to Manganese Bronze or Phosphor Bronze, at t\vo-thirds
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CHARLES METCALF. JOHN M. FERGUSON.
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(-•)
INDUSTRIAL LITERATURE
Civilization without Diversified Industries is an Impossibility
and all History Bears Witness to this Great Truth. H.C.B.
CATALOGUE
OF
Practical and Scientific Books
PUBLISHED BY
Henry Carey Baird & Co.
INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS.
810 Walnut Street, Philadelphia.
4^ Any of the Books comprised in this Catalogue will be sent by mail,
free of postage, to any address in the world, at the publication prices.
4®* A Descriptive Catalogue. 94 pages, 8vo., will be sent free and free
of postage, to any one in any part ot the world, who will furnish
his address.
4S- Where not otherwise stated, all of the Books in this Catalogue
are bound in muslin.
AMATEUR MECHANICS' WORKSHOP:
A treatise containing plain and concise directions for the
manipulation of Wood and Metals, including Casting, Forg-
ing, Brazing, Soldering and Carpentry. By the author of
the "Lathe and Its Uses." Seventh edition. Illustrated.
8vo ■ • 52.50
ARLOT.— A Complete Guide for Coach Painters:
Translated from the French of M. Arlot, Coach Painter, for
eleven years Foreman of Painting to M. Eherler, Coach
Maker, Paris. By A. A. Fesquet, Chemist and Engineer.
To which is added an Appendix, containing Information re-
specting the Materials and the Practice of Coach and Car
Painting and Varnishing in the United States and Great
Britain. i2rao |i.25
2 HENRY CAREY BAIRD & CO.'S CATALOGUE
ARMENGAUD, AMOROUX, AND JOHNSON.— The Prac-
tical Draughtsman's Book of Industrial Design, and
Machinist's and Engineer's Drawing Companion:
Forming a Complete Course of Mechanical Engineering and
Architectural Drawing. From the French of M. Armengaud
the elder, Prof, of Design in the Conservatoire of Arts and
Industry, Paris, and M. Armengaud the younger, and Amo-
roux. Civil Engineers. Rewritten and arranged with addi-
tional matter and plates, selections from and examples of
the most useful and generally employed mechanism of the
day. By William Johnson, Assoc. Inst. C. E. Illustrated
by fifty folio steel plates, and fifty wood-cuts. A new edi-
tion, 4to., cloth $5.00
ARROWSMITH.— The Paper-Hanger's Companion:
Comprising Tools, Pastes, Preparatory Work; Selection and
Hanging of Wall- Papers; Distemper Painting and Cornice-
Tinting; Stencil Work; Replacing Sash-Cord and Broken
Window Panes; and Useful Wrinkles and Receipts. By James
Arrowsmith. a New, Thoroughly Revised, and Much En-
larged Edition. Illustrated by 25 engravings, 162 pages.
(1905) $100
ASHTON.— The Theory and Practice of the Art of Design-
ing Fancy Cotton and Woolen Cloths from Sample:
Giving full instructions for reducing drafts, as well as the
methods of spooling and making out harness for cross drafts
and finding any required reed; with calculations and tables
of yarn. By Frederic T. Ashton, Designer, West Pittsfield,
Mass. With fifty-two illustrations. One vol. folio ?4.oo
ASKINSON. — Perfumes and and their Preparation :
A Comprehensive Treatise on Perfumery, containing Complete
Directions for Making Handkerchief Perfumes, Smelling-
Salts, Sachets, Fumigating Pastils; Preparations for the
Care of the Skin, the Mouth, the Hair; Cosmetics, Hair
Dyes, and other Toilet Articles. By G. W. Askinson.
Translated from the German by Isidor Furst. Revised by
Charles Rice. 32 Illustrations. 8vo $3.00
BEANS. — ^A Treatise on Railway Curves and Location of
Railroads:
By E. W. Beans, C. E. Illustrated. i2mo. Morocco. .$1.00
BELL. — Carpentry Made Easy:
Or, The Science and Art of Framing on a New and Improved
System. With Specific Instructions for Building Balloon
Frames, Barn Frarnes, Mill Frames, Warehouses, Church
Spires, etc. Comprising also a System of Bridge Building,
with Bills, Estimates of Cost, and valuable Tables. lUus-
HENRY CAREY BAIRD & CO.'S CATALOGUE 3
trated by forty-four plates, comprising nearly 200 figures.
By William E. Bell, Architect and Practical Builder.
8vo $5.00
BERSCH.— Cellulose, Cellulose Products, and Rubber
Substitutes:
Comprising the Preparation of Cellulose, Parchment-Cellu-
lose, Methods of Obtaining Sugar, Alcohol, and Oxalic Acid
from Wood-Cellulose; Production of Nitro-Cellulose and
Cellulose Esters; Manufacture of Artificial Silk, Viscose,
Celluloid, Rubber Substitutes, Oil-Rubber, and Faktis. By
Dr. Joseph Bersch. Translated by William T. Brannt.
41 Illustrations. (1904.) JS3.00
BILLINGS.— Tobacco :
Its History, Variety, Culture, Manufacture, Commerce, and
Various Modes of Use. By E. R. Billings. Illustrated by
nearly 200 engravings. 8vo $3.00
BIRD. — The American Practical Dyers' Companion:
Comprising a Description of the Principal Dye-Stuffs and
Chemicals used in Dyeing, their Natures and Uses; Mor-
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French and German processes for Bleaching and Dyeing
Silk, Wool, Cotton, Linen, Flannel, Felt, Dress Goods, Mixed
and Hosiery Yarns, Feathers, Grass, Felt, Fur, Wool, and
Straw Hats, Jute Yarn, Vegetable Ivory, Mats, Skins, Furs,
Leather, etc., etc., by Wood, Aniline, and other Processes,
together with Remarks on Finishing Agents, and Instructions
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Materials and Fabrics. By F. J. Bird, Practical Dyer,
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BIJNN. — ^A Practical Workshop Companion for Tin,
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used by Tin, Sheet-Iron and Copper-plate Workers; Practical
Geometry; Mensuration of Surface and Solids; Tables of the
Weights of Metals, Lead-pipe, etc.; Tables of Areas and
Circumferences of Circles; Japan, Varnishes, Lacquers, Ce-
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Mechanic. With One Hundred and Seventy Illustrations.
i2mo $2.50
BOOTH. — Marble Worker's Manual:
Containing Practical Information respecting Marbles in
general, their Cutting, Working and Polishing; Veneering of
Marble; Mosaics; Composition and Use of Artificial Marble,
4 HENRY CAREY BAIRD & CO.'S CATALOGUE
Stuccos, Cements, Receipts, Secrets, etc., etc. Translated
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BRANNT.— A Practical Treatise on Animal and Vegetable
Fats and Oils:
Comprising both Fixed and Volatile Oils, their Physical and
Chemical Properties and Uses, the Manner of Extracting and
Refining them, and Practical Rules for Testing them; as well
as the Manufacture of Artificial Butter and Lubricants, etc.,
with lists of American Patents relating to the Extraction,
Rendering, Refining, Decomposing and Bleaching of Fats
and Oils. By William T. Brannt, Editor of the "Techno-
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in great part Rewritten. Illustrated by 302 Engravings.
In Two Volumes. 1304 pp. 8vo $10.00
BRANNT.— A Practical Treatise on Distillation and Rec-
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Comprising Raw Materials; Production of Malt, Preparation
of Mashes and of Yeast; Fermentation; Distillation and
Rectification and Purification of Alcohol; Preparation of
Alcoholic Liquors, Liqueurs, Cordials, Bitters, Fruit Essences,
Vinegar, etc.; Examination of Materials for the Preparation
of Malt as well as of the Malt itself; Examination of Mashes
before and after Fermentation; Alcoholometry, with Numer-
ous Comprehensive Tables; and an Appendix on the Manu-
facture of Compressed Yeast and the Examination of Alcohol
and Alcoholic Liquors for Fusel Oil and other Impurities.
By William T. Brannt, Editor of "The Techno-Chemical
Receipt Book.'' Second Edition. Entirely Rewritten.
Illustrated by 105 engravings. 460 pages, 8vo. (Dec,
1903) $12.50
BRANNT.— India Rubber, Gutta-Percha and Balata:
Occurrence, Geographical Distribution, and Cultivation, Ob-
taining and Preparing the Raw Materials, Modes of Working
and Utilizing them, including Washing, Maceration, Mixing,
Vulcanizing, Rubber and Gutta-Percha Compounds, Utiliza-
tipn of Waste, etc. By William T. Brannt. Illustrated.
i2mo. A new edition in preparation.
BRANNT.— A Practical Treatise on the Manufacture of
Vinegar and Acetates, Cider, and Fruit-Wines:
Preser\'ation of Fruits and Vegetables by Canning and Evap-
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Catchups, Pickles, Mustards, etc. Edited from various
sources. By .William T. Brannt. Illustrated by 79 En-
gravings. 479 pp. 8vo (Scarce)
BRANNT.— The Metallic Alloys: A Practical Guide
For the Manufacture of all kinds of Alloys, Amalgams, and
Solders.^used by Metal Workers: together with their Chemical
HENRY CAREY BAIRD & CO.'S CATALOGUE 5
and Physical Properties and their Application in the Arts
and the Industries; with an Appendix on the Coloring of
Alloys and the Recovery of Waste Metals. By William
T. Brannt. 45 Engravings. Third, Revised, and Enlarged
Edition. 570 pages. 8vo Net, $5.00
BRANNT.— The Metal Worker's Handy-Book of Receipts
and Processes:
Being a Collection of Chemical Formulas and Practical
Manipulations for the working of all Metals; including the
Decoration and Beautifying of Articles Manufactured there-
from, as well as their Preservation. Edited from various
sources. By William T. Brannt. Illustrated. i2mo. .$2.50
BRANNT.— Petroleum :
Its History, Origin, Occurrence, Production, Physical and
Chemical Constitution, Technology, Examination and Uses;
Together with the Occurrence and Uses of Natural Gas.
Edited chiefly from the German of Prof. Hans Hoefer and Dr.
Alexander Veith, by Wm. T. Brannt. Illustrated by 3
Plates and 284 Engravings. 743 pp. 8vo $12.50
BRANNT.— The Practical Dry Cleaner, Scourer and
Garment Dyer:
Comprising Dry, Chemical, or French Cleaning; Purifica-
tion of Benzine; Removal of Stains, or Spotting; Wet Clean-
ing; Finishing Cleaned Fabrics; Cleaning and Dyeing Furs,
Skin Rugs and Mats; Cleaning and Dyeing Feathers; Clean-
ing and Renovating Felt, Straw and Panama Hats; Bleach-
ing and Dyeing Straw and Straw Hats; Cleaning and Dyeing
Gloves; Garment Dyeing; Stripping, Analysis of Textile
Fabrics. Edited by William T. Brannt, Editor of "The
Techno-Chemical Receipt Book." Fourth Edition, Revised
and Enlarged. Illustrated by Forty-One Engravings. 12
mo. 371 pp $2.50
CONTENTS: I. Dry Chemical or French Cleaning. II. Removal of
Stains, or Spotting. III. Wet Washing. IV. Finishing Cleaned Fabrics. V.
Cleaning and Dyeing Furs, Skin Rugs and Mats. VI. Cleaning and Dye-
ing Feathers. VII. Cleaning " and Renovating Felt, Straw and Panama
Hats; Bleaching and Dyeing Straw and Straw Hats. VIII. Cleaning and
Dyeing Gloves. IX. Garment Dyeing. X. Stripping Colors from Gar-
ments and Fabrics. XI. Analysis of Textile Fabrics. Index.
BRANNT.— The Soap Maker's Hand-Book of Materials
Processes and Receipts for every description of Soap includ-
ing Fats, Fat Oils and Fatty Acids; Examination of Fats and
Oils; Alkalies; Testing Soda and Potash; Machines and
Utensils; Hard Soaps; Soft Soaps; Textile Soaps; Washing
Pov^ders and Allied Products; Toilet Soaps, Medicated
Soaps, and Soap Specialties; Essential Oils and other Perfum-
ing Materials; Testing Soaps. Edited chiefly from the
German of Dr. C. Deite, A. Engelharut, F. Wiltner,
6 HENRY CAREY BAIRD & CO.'S CATALOGUE
and numerous other Experts. With Additions by William
T. Brannt, Editor of "TheTechno-Chemical Receipt Book."
Illustrated by Fifty-Four Engravings. Second edition, Re-
vised and in great part Re- Written. 535 pp. 8vo JS6.00
BRANNT. — Varnishes, Lacquers, Printing Inks and Seal-
ing Waxes:
Their Raw Materials and their Manufacture, to which is
added the Art of Varnishing and Lacquering, including the
Preparation of Putties and of Stains for Wood, Ivory, Bone,
Horn, and Leather. By William T. Brannt. Illustrated
by 39 Engravings, 338 pages. i2mo $3-oo
BRANNT— WAHL.— TheTechno-Chemical Receipt Book:
Containing several thousand Receipts covering the latest,
most important, and most useful discoveries in Chemical
Technology, and their Practical Application in the Arts and
the Industries. Edited chiefly from the German of Drs.
Winckler, Eisner, Heintze, Mierzinski, Jacobsen, Keller and
Heinzerling, with additions by Wm. T. Brannt and Wm. H.
Wahl, Ph. D. Illustrated by 78 engravings. l2mo. 495
pages I2.00
BROWN. — Five Hundred and Seven Mechanical Move-
ments:
Embracing all those which are most important in Dynamics,
Hydraulics, Hydrostatics, Pneumatics, Steam Engines, Mill
and other Gearing, Presses, Horology, and Miscellaneous
Machinery; and including many movements never before
published, and several of which have only recently come into
use. By Henry T. Brown $1.00
BULLOCK.— The Rudiments of Architectui'e and Build-
ing:
For the use of Architects, Builders, Draughtsmen, Machin-
ists, Engineers and Mechanics. Edited by John Bullock,
author of "The American Cottage Builder." Illustrated
by 250 Engravings. 8vo ^2.50
BYRNE.— Hand-Book for the Artisan, Mechanic, and
Engineer:
Comprising the Grinding and Sharpening of Cutting Tools,
Abrasive Processes, Lapidary Work, Gem and Glass En-
graving, Varnishing and Lacquering, Apparatus, Materials
and Processes for Grinding and Polishing, etc. By Oliver
Byrne. Illustrated by 185 wood engravings. 8vo $4.00
BYRNE.— Pocket-Book for Railroad and Civil Engineers:
Containing New, Exact and Concise Methods for Laying out
Railroad Curves, Switches, Frog Angles and Crossings; the
Staking out of work; Levelling; the Calculation of Cuttings;
Embankments; Earthwork, etc. By Oliver Byrne. i8mo.,
full bound, pocketbook form ; $1.50
HENRY CAREY BAIRD & CO.'S CATALOGUE 7
BYRNE.— The Practical Metal- Worker's Assistant:
Comprising Metallurgic Chemistry; the Arts of Working all
Metals and Alloys; Forging of Iron and Steel; Hardening and
Tempering; Melting and Mixing; Casting and Founding;
Works in Sheet Metals; the Process Dependent on the Duc-
tility of the Metals; Soldering; etc. By John Percy. The
Manufacture of Malleable Iron Castings, and Improvements
in Bessemer Steel. By A. A. Fesquet, Chemist and En-
gineer. With over Six Hundred Engravings, Illustrating
every Branch of the Subject. 8vo $3-5o
CABINET MAKER'S ALBUM OF FURNITURE:
Comprising a Collection of Designs for various Styles of
Furniture. Illustrated by Forty-eight Large and Beau-
tifully Engraved Plates. Oblong, 8vo $1.50
CALLINGHAM.— Sign Writing and Glass Embossing:
A complete Practical Illustrated Manual of the Art. By
James Callingham. To which are added Numerous Alpha-
bets and the Art of Letter Painting Made Easy. By James
C. Badenoch. 258 pages. i2mo $1.50
CAREY.— A Memoir of Henry C. Carey:
By Dr. Wm. Elder. With a portrait. Svo., cloth 75
CAREY.— The Works of Henry C. Carey:
Manual of Social Science. Condensed from Carey's
"Principles of Social Science." By Kate McKean. i vol.
i2mo $2.00
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Past, Present and Future. 8vo $2.50
Principles of Social Science. 3 volumes, 8vo $10.00
The Slave-Trade, Domestic and Foreign; Why it Exists,
and How it may be Extinguished (1853). 8vo $2.00
The Unity of Law: As Exhibited in the Relations of Phys-
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COOLEY. — A Complete Practical Treatise on Perfumery:
Being a Hand-book of Perfumes, Cosmetics and other Toilet
Articles, with a Comprehensive Collection of Formulae. By
Arnold Cooley. i2mo $1.00
COURTNEY.^The Boiler Maker's Assistant In Drawing,
Templating, and Calculating Boiler Work and Tank
Work, etc.
Revised by D. K. Clark. 102 ills. Fifth edition 80
COURTNEY.— The Boiler Maker's Ready Reckoner:
With Examples of Practical Geometry and Templating. Re-
vised by D. K. Clark, C. E. 37 illustrations. Fifth edi-
tion r $i-6o
8 HENRY CAREY BAIRD & CO.'S CATALOGUE
CRISTIANI.— A Technical Treatise on Soap and Candles:
With a Glance at the Industry of Fats and Oils. By R. S.
Cristiani, Chemist. Author of "Perfumery and Kindred
Arts. " Illustrated by 176 engravings. 581 pages, 8vo. .I15.00
CROSS.— The Cotton Yarn Spinner:
Showing how the Preparation should be arranged for Differ-
ent Counts of Yarns by a System more uniform than has hith-
erto been practiced; by having a Standard Schedule from
which we make all our Changes. By Richard Cross. 122
pp. i2mo 75
DAVIDSON.— A Practical Manual of House Painting,
Graining, Marbling, and Sign-Writing:
Containing full information on the processes of House Paint-
ing in Oil and Distemper, the Formation of Letters and
Practice of Sign-Writing, the Principles of Decorative Art,
a Course of Elementary Drawing for House Painters, Writers,
etc.", and a Collection of Useful Receipts. With nine colored
illustrations of Woods and Marbles, and numerous wood en-
gravings. By Ellis A. Davidson. i2mo $2.00
DA VIES. — A Treatise on Earthy and Other Minerals and
Mining:
By D. C. Davies, F. G. S., Mining Engineer, etc. Illustrated
by 76 Engravings. l2mo fc.oo
DAVIES.— ^A Treatise on Metalliferous Minerals and
Mining:
By D. C. Davies, F. G. S., Mining Engineer, Examiner of
Mines, Quarries and Collieries. Illustrated by 148 engrav-
ings of Geological Formations, Mining Operations and Ma-
chinery, drawn from the practice of all parts of the world.
Fifth Edition, thoroughly Revised and much Enlarged by
his son, E. Henry Davies. l2mo. 524 pages $5-00
DAVIS. — A Practical Treatise on the Manufacture of
Brick, Tiles and Terra-Cotta:
Including Stiff Clay, Dry Clay, Hand Made, Pressed or Front,
and Rbadway Paving Brick, Enamelled Brick, with Glazes
and Colors, Fire Brick and Blocks, Silica Brick, Carbon Brick,
Glass Pots, Retorts, Architectural Terra-Cotta, Sewer Pipe,
Drain Tile, Glazed and Unglazed Roofing Tile, Art Tile, Mo.saics,
and Imitation of Intarsia or Inlaid Surfaces. Comprising every
product of Clay employed in Architecture, Engineering, and
the Blast Furnace. With a Detailed Description of the Differ-
ent Clays employed, the Most Modern Machinery, Tools,
and Kilns used, and the Processes for Handling, Disintegrat-
ing, Tempering, and Moulding the Clay into Shape, Drying,
Setting, and Burning. By Charles Thomas Davis. Third
Edition. Revised and in great part rewritten. Illustrated
by 261 engravings. 662 pages ■ (Scarce.)
HENRY CAREY BAIRD & CO.'S CATALOGUE 9
DAVIS.— The Manufacture of Paper:
Being a Description of the various Processes for the Fabrica-
tion, Coloring and Finishing of every kind of Paper, Includ-
ing the Different Raw Materials and the Methods for De-
termining their Values, the Tools, Machines and Practical
Details connected with an intelligent and a profitable prose-
cution of the art, with special reference to the best American
Practice. To which are added a History of Paper, complete
Lists of Paper-Making, Materials, List of American Machines,
Tools and Processes used in treating the Raw Materials, and
in Making, Coloring and Finishing Paper. By Charles T.
Davis. Illustrated by 156 Engravings. 608 pages. ' 8vo.
$6.00
DAWIDOWSKY— BRANNT.— A Practical Treatise on the
Raw Materials and Fabrication of Glue, Gelatine,
Gelatine Veneers and Foils, Isinglass, Cements,
Pastes, Mucilages, etc.:
Based upon Actual Experience. By F. Dawidowsky, Tech-
nical Chemist. Translated from the German, with extensive
additions, including a description of the most Recent American
Processes, by William T. Brannt. 2d revised edition, 350
pages. (1965.) Price $3-00
DEITE. — ^A Practical Treatise on the Manufacture of
Perfumery:
Comprising directions for making all kinds of Perfumes,
Sachet Powders, Fumigating Materials, Dentifrices, Cos-
metics, etc., with a full account of the Volatile Oils, Balsams,
Resins, and other Natural and Artificial Perfume-substances,
including the Manufacture of Fruit Ethers, and tests of their
purity. By Dr. C. Deite, assisted by L. Borchert, F.
EiCHBAUM, E. Kugler, H. Toeffner, and other experts.
From the German, by Wm. T. Brannt. 28 Engravings.
358 pages. 8vo iPS-OO
DE KONINCK— DIETZ.— A Practical Manual of Chemical
Analysis and Assaying:
As applied to the Manufacture of Iron from its Ores, and to
Cast Iron, Wrought Iron, and Steel, as found in Commerce.
By L. L. DeKoninck, Dr. Sc, and E. Dietz, Engineer. Ed-
ited with Notes, by Robert Mallet, F. R. S., F. S. G., M.
I C. E., etc. American Edition, Edited with Notes and an
Appendix on Iron Ores, by A. A. Fesquet, Chemist and
Engineer. i2mo jsi.oo
DIETERICHS.— A Treatise on Friction, Lubrication,
Oils and Fats:
The Manufacture of Lubricating Oils, Paint Oils, and ot
Grease, and the Testing of Oils. By E. F. Dieterichs,
10 HENRY CAREY BAIRD & CO.'S CATALOGUE
Member of the Franklin Institute; Member National Associa-
tion of Stationary Engineers; Inventor of Dieterichs' Valve-
Oleum Lubricating Oils. i2mo. (1906.) A practical book
by a practical man $i-25
DUNCAN. — Practical Surveyor's Guide:
Containing the necessary information to make any person of
common capacity, a finished land surveyor, without the aid
of a teacher. By Andrew Duncan. Revised. 72 Engrav-
ings. 214 pp. i2mo $1.50
DUPLAIS.— A Treatise on the Manufacture and Dis-
tillation of Alcoholic Liquors:
Comprising Accurate and Complete Details in Regard to
Alcohol from Wine, Molasses, Beets, Grain, Rice, Potatoes,
Sorghum, Asphodel, Fruits, etc.; with the Distillation and
Rectification of Brandy, Whiskey, Rum, Gin, Swiss Absinthe,
etc., the Preparation of Aromatic Waters, Volatile Oils or
Essences, Sugars, Syrups, Aromatic Tinctures, Liqueurs,
Cordial Wines, Effervescing Wines, etc., the Ageing of Brandy
and the improvement of Spirits, with Copious Directions
and Tables for Testing and Reducing Spirituous Liquors, etc.,
etc. Translated and Edited from the French of MM. Du-
PLAis. By M. McKennie, M. D. Illustrated. 743 pp.
8vo *i5-oo
EDWARDS.— A Catechism of the Marine Steam- Engine:
For the use of Engineers, Firemen, and Mechanics. A Prac-
tical Work for Practical Men. By Emory Edwards, Me-
chanical Engineer. Illustrated by sixty-three Engravings,
including examples of the most modern Engines. Third
edition, thoroughly revised, with much additional matter.
i2mo. 414 pages $1.50
EDWARDS. — ^American Marine Engineer, Theoretical
and Practical:
With Examples of the latest and most approved American
Practice. By Emory Edwards. 85 Illustrations. lamo.
$1.50
EDWARDS. — Modern American Locomotive Engines:
Their Design, Construction and Management. By Emory
Edwards. Illustrated. i2mo $1.50
EDWARDS. — 900 Examination Questions and Answers:
For Engineers and Firemen (Land and Marine) who desire
to obtain a United States Government or State License.
Pocket-book form, gilt edge ?i.50
EDWARDS.— The American Steam Engineer:
Theoretical and Practical, with examples of the latest and
most approved American practice in the design and con-
struction of Steam Engines and Boilers. For the use of
HENRY CAREY BAIRD & CO.'S CATALOGUE ii
Engineers, machinists, boiler-makers, and engineering stu-
dents. By Emory Edwards. Fully illustrated. 419 pages.
i2mo $1.50
EDWARDS.— The Practical Steam Engineer's Guide:
In the Design, Construction, and Management of American
Stationary, Portable, and Steam Fire-Engines, Steam Pumps,
Boilers, Injectors, Governors, Indicators, Pistons and Rings,
Safety Valves and Steam Gauges. For the use of Engineers,
Firemen, and Steam Users. By Emory Edwards. Illus-
trated by 119 engravings. 420 pages. i2mo $2.00
ELDER. — Conversations on the Principal Subjects of
Political Economy:
By Dr. William Elder. 8vo $1.50
ELDER.— Questions of the Day:
Economic and Social. By Dr. William Elder. 8vo. $3.00
ERNI AND BROWN.— Mineralogy Simplified:
Easy Methods of Identifying Minerals, including Ores, by
Means of the Blow-pipe, by Flame Reactions, by Humid
Chemical Analysis, and by Physical Tests. By Henri
Erni, a. M., M. D. Fourth Edition, revised, re-arranged
and with the addition of entirely new matter, including Tables
for the Determination of Minerals by Chemicals and Pyrog-
nostic Characters, and by Physical Characters. By Amos
P. Brown, E. M., Ph. D. 464 pp. Illustrated by 123 En-
gravings, pocket-book form, full flexible morocco, gilt edges.
$2.50
FAIRBAIRN. — ^The Principles of Mechanism and Machi-
nery of Transmission:
Comprising the Principles of Mechanism, Wheels, and Pul-
leys, Strength and Proportion of Shafts, Coupling of Shafts,
and Engaging and Disengaging Gear. By Sir William
Fairbairn, Bart., C. E. Beautifully illustrated by over 150
wood-cuts. In one volume, l2mo $2.00
FLEMING.— Narrow Gauge Railways in America:
A Sketch of their Rise, Progress, and Success. Valuable
Statistics as to Grades, Curves, Weight of Rail, Locomotives,
Cars, etc. By Howard Fleming. Illustrated. 8vo. ..$1.00
FLEMMING.— Practical Tanning:
A Handbook of Modern Processes, Receipts, and Sugges-
tions for the Treatment of Hides, Skins, and Pelts of Every
Description. By Lewis A. Flemming, American Tanner.
630 pp, 8vo. 1910 $6.00
FORSYTH.— Book of Designs for Headstones, Mural, and
other Monuments:
Containing 78 Designs. By James Forsyth, With an In-
troduction by Charles Boutell, M. A. 4to. Cloth., .fo.oo
12 HENRY CAREY BAIRD & CO.'S CATALOGUE
GARDNER.— Everybody's Paint Book:
A Complete Guide to the Art of Outdoor and Indoor Paint-
ing. . 38 illustrations. i2mo. 183 pp $1^00
GARDNER.— The Painter's Encyclopaedia:
Containing Definitions of all Important Words in the Art of
Plain and Artistic Painting, with Details of Practice in Coach,
Carriage, Railway Car, House, Sign, and Ornamental Paint-
ing, including Graining, Marbling, Staining, Varnishing,
Polishing, Lettering, Stenciling, Gilding, Bronzing, etc. By
Franklin B. Gardner. 158 illustrations. i2mo. 427 pp.
$2.00
GEE.— The Goldsmith's Handbook:
Containing full instructions for the Alloying and Working of
Gold, including the Art of Alloying, Melting, Reducing, Color-
ing, Collecting, and Refining ; the Processes of Manipulation, Re-
covery of Waste; Chemical and Physical Properties of Gold;
with a New System of Mixing its Alloys; Solders, Enamelsj
and other Useful Rules and Recipes. By George E. Gee.
l2mo $1.25
GEE. — ^The Jeweler's Assistant in the Art of Working in
Gold:
A Practical Treatise for Masters and Workmen. l2mo. $3.00
GEE.— The Silversmith's Handbook:
Containing full instructions for the Alloying and Working of
Silver, including the different modes of Refining and Melting
the Metal; its Solders; the Preparation of Imitation Alloys;
Methods of Manipulation; Prevention of Waste; Instructions
for Improving and Finishing the Surface of the Work; together
with other Useful Information and Memoranda. By George
E. Gee. Illustrated. i2mo $1-25
GOTHIC ALBUM FOR CABINET-MAKERS:
Designs for Gothic Furniture. Twenty-three plates. Ob-
long $1.00
GRANT.— A Handbook on the Teeth of Gears:
Their Curves, Properties, and Practical Construction. By
George B. Grant. Illustrated. Third Edition, enlarged.
8vo Ii.oo
GREGORY.— Mathematics for Practical Men:
Adapted to the Pursuits of Surveyors, Architects, Mechan-
ics, and Civil Engineers. By Olinthus Gregory. 8vo.,
plates $3.00
GRISWOLD.— Railroad Engineer's Pocket Companion
for the Field:
Comprising Rules for Calculating Deflection Distances and
Angles, Tangential Distances and Angles and all Necessary
Tables for Engineers; also the Art of Levelling from Prelim-
HENRY CAREY BAIRD & CO.'S CATALOGUE 13
inary Survey to the Construction of Railroads, intended
Expressly for the Young Engineer, together with Numerous
Valuable Rules and Examples. By W. Griswold. lamo.
pocketbook form .$1.50
GRUNER.— Studies of Blast Furnace Phenomena:
By M. L. Gruner, President of the General Council of Mines
of France, and lately Professor of Metallurgy at the Ecole defe
Mines. Translated, with the author's sanction, with an Ap-
pendix, by L. D. B. Gordon, F. R. S. E., F. G. S. 8vo. $2.50
Hand-Book of Useful Tables for the Lumberman, Farmer
and Mechanic:
Containing Accurate Tables of Logs Reduced to Inch Board
Measure, Plank, Scantling and Timber Measure; Wages and
Rent, by Week or Month; Capacity of Granaries, Bins and
Cisterns; Land Measure, Interest Tables with Directions
for finding the Interest on any sura at 4, 5, 6, 7 and 8 per cent.,
and many other Useful Tables. 32mo., boards. 186 pages.
•25
HASERICK.— The Secrets of the Art of Dyeing Wool,
Cotton and Linen:
Including Bleaching and Coloring Wool and Cotton Hosiery
and Random Yarns. A Treatise based on Economy and
Practice. By E. C. Haserick. Illustrated by 323 Dyed
Patterns of the Yarns or Fabrics. 8vo $4.50
HATS AND FELTING:
A Practical Treatise on their Manufacture. By a Practical
Hatter. Illustrated by Drawings of Machinery, etc. 8vo.
1 1. 00
HAUPT.— A Manual of Engineering Specifications and
Contracts :
By Lewis M. Haupt, C. E. Illustrated with numerous
maps. 328 pp. 8vo I2.00
HAUPT. — Street Railway Motors:
With Descriptions and Cost of Plants and Operation of the
Various Systems now in Use. l2mo $1.50
HAUPT. — The Topographer, His Instruments and Meth-
ods.
By Lewis M. H.\upt, A. M., C. E. Illustrated with numer-
ous plates, maps and engravings. 247 pp. 8vo $2.00
HULME.— Worked Examination Questions in Plane
Geometrical Drawing:
For the Use of Candidates for the Royal Military Academy,
Woolwich; the Royal Military College, Sandhurst; the In-
dian Civil Engineering College, Cooper's Hill; Indian Public
Works and Telegraph Department; Royal Marine Light In-
14 HENRY CAREY BAIRD & CO.'S CATALOGUE
fantry; the Oxford and Cambridge Local Examinations, etc.
By F. Edward Hulme, F. L. S., F. S. A., Art-Master Marl-
borough College. Illustrated by 300 examples. Small
quarto f l.oo
KELLEY. — Speeches, Addresses, and Letters on Industrial
and Financial Questions:
By Hon. William D. Kelley, M. C. 544 pages. 8vo. $2.00
KEMLO.— Watch-Repairer's Hand-Book:
Being a Complete Guide to the Young Beginner, in Taking
Apart, Putting Together, and Thoroughly Cleaning the
English Lever and other Foreign Watches, and all American
Watches. By F. Kelmo, Practical Watchmaker. With Il-
lustrations. i2mo $1.25
KICK. — Flour Manufacture:
A Treatise on Milling Science and Practice. By Frederick
Kick, Imperial Regierungsrath, Professor of Mechanical
Technology in the Imperial German Polytechnic Institute,
Prague. Translated from the second enlarged and revised
edition with supplement by H. H. P. Powles, Assoc. Memb.
Institution of Civil Engineers. Illustrated with 28 Plates,
and 167 Wood-cuts. 367 pages. 8vo $10.00
KINGZETT.— The History, Products, and Processes of
the Alkali Trade:
Including the most Recent Improvements. By Charles
Thomas Kingzett, Consulting Chemist. With 23 illu.stra-
tions. 8vo $2.00
KIRK. — A Practical Treatise on Foundry Irons:
Comprising Pig Iron, and Fracture Grading of Pig and Scrap
Irons; Scrap Irons; Mixing Irons; Elements and Metalloids:
Grading Iron by Analysis; Chemical Standards for Iron
Castings; Testing Cast Iron; Serai-Steel; Malleable Iron;
Etc., Etc. By Edward Kirk, Practical Moulder and Melter,
Consulting Expert in Melting. Illustrated. 294 pages.
8vo. 1911 I3.00
KIRK.— The Cupola Furnace:
A Practical Treatise on the Construction and Management of
Foundry Cupolas. By Edward Kirk, Practical Moulder and
Melter, Consulting Expert in Melting. Illustrated by 106
engravings. Third Edition, revised and enlarged. 482
pages. 8vo. 1910 $3.50
KOENIG.— Chemistry Simplified:
A Course of Lectures on the Non-Metals, Based upon the
Natural Evolution of Chemistry. Designed Primarily for
Engineers. By George Augustus Koenig, Ph. D., A. M.,
E. M., Professor of Chemistry, Michigan College of Mines,
Houghton. Illustrated by 103 Original Drawings. 449 pp.
i2mo. (1906) J2.25
HENRY CAREY BAIRD & CO.'S CATALOGUE 15
LANGBEIN.— A Complete Treatise on the Electro-Deposi-
tion of Metals:
Comprising Electro-Plating and Galvanoplastic Operations,
the Deposition of Metals by the Contact and Immersion Pro-
cesses, the Coloring of Metals, the Methods of Grinding and
Polishing, as well as the Description of the Voltaic Cells,
Dynamo-Electric Machines, Thermopiles, and of the Materi-
als and Processes Used in Every Department of the Art.
Translated from the Fifth German Edition of Di^ George
Langbein, Proprietor of a Manufactory for Chemical Pro-
ducts, Machines, Apparatus and Utensils for Electro-Platers,
and of an Electro-Plating Establishment in Leipzig. With
Additions by William T. Brannt, Editor of "The Techno-
Chemical Receipt Book." Sixth Edition, Revised and En-
larged. Illustrated by 163 Engravings. 8vo. 725 pages.
(1909) fc-oo
LARKIN.— The Practical Brass and Iron Founder's
Guide:
A Concise Treatise on Brass Founding, Moulding, the Metals
and their Alloys, etc.; to which are added Recent Improve-
ments in the Manufacture of Iron, Steel by the Bessemer
Process, etc., etc. By James Larkin, late Conductor of the
Brass Foundry Department in Reany, Neafie & Co.'s Penn
Works, Philadelphia. New edition, revised, with extensive
additions. 414 pages. i2mo S2.50
LEHNER.— The Manufacture of Ink:
Comprising the Raw Materials, and the Preparation of
Writing, Copying and Hektograph Inks, Safety Inks, Ink
Extracts and Powders, etc. Translated from the German
of SiGMUND Lehner, with additions by William T. Brannt.
Illustrated. i2mo $2.00
LEROUX. — A Practical Treatise on the Manufacture of
Worsteds and Carded Yarns:
Comprising Practical Mechanics, with Rules and Calcula-
tions applied to Spinning; Sorting, Cleaning, and Scouring
Wools; the English and French Methods of Combing, Draw-
ing, and Spinning Worsteds, and Manufacturing Carded
Yarns. Translated from the French of Charles Leroux,
Mechanical Engineer and Superintendent of a Spinning-Mill,
by Horatio Paine, M. D., and A. A. Fesquet, Chemist and
Engineer. Illustrated by twelve large Plates. 8vo $3.00
LESLIE.— Complete Cookery:
Directions for Cookery in its Various Branches. By Miss
Leslie. Sixtieth thousand. Thoroughly revised, with the
additions of New Receipts. i2mo $1.00
LE VAN.— The Steam Engine and the Indicator:
Their Origin and Progressive Development; including the
Most Recent Examples of Steam and Gas Motors, together
i6 HENRY CAREY BAIRD & CO.'S CATALOGUE
with the Indicator, its Principles, its Utility, and its Applica-
tion. By William Barnet Le Van. Illustrated by 205
Engravings, chiefly of Indicator-Cards. 469 pp. 8vo. J2.00
LIEBER.— Assayer's Guide:
Or, Practical Directions to Assayers, Miners, and Smelters,
for the Tests and Assays, by Heat and by Wet Processes, for
the Ores of all the principal Metals, of Gold and Silver Coins
and alloys, and of Coal, etc. By Oscar M. Lieber. Re-
vised. 283 pp. i2mo. r jSi-So
Lockwood's Dictionary of Terms:
Used in the Practice of Mechanical Engineering, embracing
those Current in the Drawing Office, Pattern Shop, Foundry,
Fitting, Turning, Smith's and Boiler Shops, etc., etc., com-
prising upwards of Six Thousand Definitions. Edited by a
Foreman Pattern Maker, author of "Pattern Making." 417
PP- i2mo $3.75
LUKIN.— The Lathe and Its Uses:
Or Instruction in the Art of Turning Wood and Metal. In-
cluding a Description of the Most Modern Appliances for the
Ornamentation of Plane and Curved Surfaces, an Entirely
Novel Form of Lathe for Eccentric and Rose-Engine Turning;
A Lathe and Planing Machine Combined; and Other Valu-
able Matter Relating to the Art. Illustrated by 462 engrav-
ings. ' Seventh edition. 315 pages. 8vo 14-25
MAUCHLINE.— The Mine Foreman's Hand-Book:
Of Practical and Theoretical Information on the Opening,
Ventilating, and Working of Collieries. Questions and An-
swers on Practical and Theoretical Coal Mining. Designed
to Assist Students and Others in Passing Examinations for
Mine Foremanships. By Robert Mauchline.. 3d Edi-
tion. Thoroughly Revised and Enlarged by F. Ernest
Brackett. 134 engravings. 8vo. 378 pages. (1905.) fe.75
MOLESWORTH.— Pocket-Bpok of Useful Formulae and
Memoranda for Civil and Mechanical Engineers.
By Guilford L. Molesworth, Member of the Institution of
Civil Engineers, Chief Resident Engineer of the Ceylon
Railway. Full-bound in Pocketbook form $1.00
MOORE. — The Universal Assistant and the Complete
Mechanic:
Containing over one million Industrial Facts, Calculatiofis,
Receipts, Processes, Trades Secrets, Rules, Business Forms,
Legal Items, etc., in every occupation, from the Household
to the Manufactory. By R. Moore. Illustrated by 500
Engravings. i2mo $2. go
HENRY CAREY BAIRD & CO.'S CATALOGUE 17
NAPIER.— A System of Chemistry Applied to Dyeing:
By James Napier, F. C. S. A New and Thoroughly Revised
Edition. Completely brought up to the present state of the
Science, including the Chemistry of Coal Tar Colors, by A.
A. Fesquet, Chemist and Engineer. With an Appendix on
Dyeing and Calico Printing, as shown at the Universal Ex-
position, Paris, 1867. Illustrated. 8vo. 422 pages. . .$2.00
NICHOLLS.— The Theoretical and Practical Boiler-Maker
and Engineer's Reference Book:
Containing a variety of Useful Iriformation for Employers
of Labor, Foremen and Working Boiler-Makers, Iron,
Copper, and Tinsmiths, Draughtsmen, Engineers, the Gen-
eral Steam-using Public, and for the Use of Science Schools
and classes. By Samuel Nicholls. Illustrated by sixteen
plates. i2mo ,. . .$2.50
NICHOLSON.— A Manual of the Art of Bookbinding:
Containing full instructions in the different Branches of For-
warding, Gilding, and Finishing. Also, the Art of MarbUng
Book-edges and Paper. By James B. Nichollson. Il-
lustrated. i2mo., cloth $2.25
NYSTROM.— On Technological Education and the Con-
struction of Ships and Screw Propellers :
For Naval and Marine Engineers. By John W. Nystrom,
late Acting Chief Engineer, U. S. N. Second edition, revised,
with additional matter. Illustrated by seven engravings.
i2mo jfi.oo
O'NEILL.— A Dictionary of Dyeing and Calico Printing:
Containing a brief account of all the Substances and Processes
in use in the Art of Dyeing and Printing Textile Fabrics;
with Practical Receipts and Scientific Information. By
Charles CNeh-l, Analytical Chemist. To which is added
an Essay on Coal Tar Colors and their application to Dyeing
and Calico Printing. By A. A. Fesquet, Chernist and En-
gineer. With an appendix on Dyeing and Calico Printing,
as shown at the Universal Exposition, Paris, 1867. 8vo.
491 pages $2.00
ORTON.— Underground Treasures:
How and Where to Find Them. A Key for the Ready De-
termination of all the Useful Minerals within the United
States. By James Orton, A. M., Late Professor of Natural
History in Vassar College, N. Y.; author of the "Andes and
the Amazon," etc. A New Edition, with An Appendix on
Ore Deposits and Testing Minerals. (1901.) Illustrated.
OSBORN.— A Practical Manual of Minerals, Mines and
Mining: ^ , . „ • •
Comprising the Physical Properties, Geologic Position;
Local Occurrence and Associations of the Useful Minerals,
i8 HENRY CAREY BAIRD & CO.'S CATALOGUE
their Methods of Chemical Analysis and Assay; together
with Various Systems of Excavating and Timbermg, Brick
and Masonry Work, during Driving, Lining, Bracing and
other Operations, etc. By Prof. H. S. Osborn LL. D.,
Author of "The Prospector's Field-Book and Guide. 171
engravings. Second Edition, revised. 8vo ?4-50
OSBORN.— The Prospector's Field Book and Guide:
In the Search For and the Easy Determination of Ores and
Other Useful Minerals. By Prof. H. S. Osborn, LL. D.
Illustrated by 66 Engravings. Eighth Edition. Revised
and Enlarged. 401 pages. i2mo. (1910-) *l-50
OVERMAN.— The Moulder's atid Founder's Pocket Guide:
A Treatise on Moulding and Founding in Green-sand, Dry-
sand, Loam, and Cement; the Moulding of Machine Frames,
Mill-gear, Hollow Ware, Ornaments, Trinkets, Bells, and
Statues; Description of Moulds for Iron, Bronze, Brass, and
other Metals; Plaster of Paris, Sulphur, Wax, etc.; the Con-
struction of Melting Furnaces, the Melting and Founding of
Metals; the Composition of Alloys and their Nature, etc., etc.
By Frederick Overman, M. E. A new Edition, to which is
added a Supplement on Statuary and Ornamental Moulding,
Ordnance, Malleable Iron Castings, etc. By A. A. Fesquet,
Chemist and Engineer. Illustrated by 44 engravings. i2mo.
$2.00
PAINTER, GILDER, AND VARNISHER'S COMPANION:
Comprising the Manufacture and Test of Pigments, the Arts
of Painting, Graining, Marbling, Staining, Sign-writing,
Varnishing, Glass-staining, and Gilding on Glass; -together
with Coach Painting and Varnishing, and the Principles of
the Harmony and Contrast of Colors. Twenty-seventh
Edition. Revised, Enlarged, and in great part Rewritten.
By William T. Brannt, Editor of "Varnishes, Lacquers,
Printing Inks and Sealing Waxes. " Illustrated. 395 pp.
l2mo $1-50
PERCY.— The Manufacturing of Russian Sheet-Iron:
By John Percy, M. D., F. R. S. Paper 25
POSSELT.— Cotton Manufacturing:
Part I. Dealing with the Fibre, Ginning, Mixing, Picking,
Scutching and Carding. By E. A. Posselt. 104 illustra-
tions, 190 pp $3.00
Part 11. Combing, Drawing, Roller Covering and Fly Frame,
$3.00
POSSELT.— The Jacquard Machine Analysed and Ex-
plained :
With an Appendix on the Preparation of Jacquard Cards, and
Practical Hints to Learners of Jacquard Designing. By E. A.
HENRY CAREY BAIRD & CO.'S CATALOGUE 19
PossELT. With 230 illustrations and numerous diagrams.
127 pp. 4to $3.00
POSSELT. — Recent Improvements in Textile Machinery
Relating to Weaving:
Giving the Most Modern Points on the Construction of all
Kinds of Looms, Warpers, Beamers, Slashers, Winders,
Spoolers, Reeds, Temples, Shuttles, Bobbins, Heddles, Heddle
Frames, Pickers, Jacquards, Card Stampers, Etc., Etc. By
E. A. PossELT. 4to. Part I, 600 ills.; Part 11, 600 ills.
Each part $3.00
POSSELT. — Recent Improvements in Textile Machinery,
Part III:
Processes Required for Converting Wool, Cotton, Silk, from
Fibre to Finished Fabric, Covering both Woven and Knit
Goods; Construction of the most Modern Improvements in
Preparatory Machinery, Carding, Combing, Drawing, and
Spinning Machinery, Winding, Warping, Slashing Machinery,
Looms, Machinery for Knit Goods, Dye Stuffs, Chemicals,
Soaps, Latest Improved Accessories Relating to Construc-
tion and Equipment of Modern Textile Manufacturing Plants.
By E. A. PossELT. Completely Illustrated. 4to $7.50
POSSELT.— Technology of Textile Design:
The Most Complete Treatise on the Construction and Appli-
cation of Weaves for all Textile Fabrics and the Analysis of
Cloth. By E. A. PossELT. 1,500 illustrations. 4to fo.oo
POSSELT.— Textile Calculations:
A Guide to Calculations Relating to the Manufacture of all
Kinds of Yarns and Fabrics, the Analysis of Cloth, Speed,
Power and Belt Calculations. By E. A. Posselt. Illus-
trated. 4to ' $2.00
REGNAULT.— Elements of Chemistry:
By M. V. Regnault. Translated from the French by T.
Forrest Betton, M.D., and edited, with Notes, by James
C. Booth, Melter and Refiner U. S. Mint, and William L.
Faber, Metallurgist and Mining Engineer. Illustrated by
nearly 700 wood-engravings. Comprising nearly 1 ,500 pages.
In two volumes, 8vo., cloth $5-00
RICH.— Artistic Horse-Shoeing:
A Practical and Scientific Treatise, giving Improved Methods
of Shoeing, with Special Directions for Shaping Shoes to Cure
Different Diseases of the Foot, and for the Correction of
Faulty Action in Trotters. By George E. Rich. 362 Illus-
trations. 217 pages. i2mo $2.00
RICHARDS.— Aluminium :
Its History, Occurrence, Properties, Metallurgy and Applica-
tions including its Alloys. By Joseph W. Richards, A. C,
20 HENRY CAREY BAIRD & CO.'S CATALOGUE
Chemist and Practical Metallurgist, Member of the Deutsche
Chemische Gesellschaft. lUust. Third edition, enlarged
and revised (1895) $6.00
RICHARDSON.— Practical Blacksmithing :
A Collection of Articles Contributed at Different Times by
Skilled Workmen to the columns of "The Blacksmith and
Wheelwright," and Covering nearly the Whole Range of
Blacksmithing, from the Simplest Job of Work to some of the
most Complex Forgings. Compiled and Edited by M. T.
Richardson.
Vol. I. 210 Illustrations. 224 pages. l2mo $1.00
Vol. II. 230 Illustrations. 262 pages. l2mo $l.oo
Vol. III. 390 Illustrations. 307 pages. i2mo jSi.oo
Vol. IV. 226 Illustrations. 276 pages. i2mo ji.oo
RICHARDSON.— Practical Carriage Building:
Comprising Numerous Short Practical Articles upon Carriage
and Wagon Woodwork; Plans for Factories; Shop and Bench
Tools; Convenient Appliances for Repair Work; Methods of
Working; Peculiarities of Bent Timber; Construction of
Carriage Parts; Repairing Wheels; Forms of Tenons and Mor-
tises; Together with a Variety of Useful Hints and Sugges-
tions to Woodworkers. Compiled by M. T. Richardson.
Vol. I. 228 Illustrations. 222 pages $1.00
Vol. II. 283 Illustrations. 280 pages $l.oo
RICHARDSON.— The Practical Horseshoer:
Being a Collection of Articles on ' Horseshoeing in all its
Branches which have appeared from time to time in the col-
umns of "The Blacksmith and Wheelwright," etc. Com-
piled and edited by M. T. Richardson. 174. Illustrations,
jfi.oo
RIFFAULT, VERGNAUD, and TOUSSAINT.— A Practical
Treatise on the Manufacture of Colors for Painting:
Comprising the Origin, Definition, and Classification of Colors,
the Treatment of the Raw Materials; the best Formulae and the
Newest Processes for the Preparation of every description of
Pigment, and the Necessary Apparatus and Directions for
its use; Dryers; the Testing, Application, and Qualities of
Paints, etc., etc. By MM. Riffault, Vergnaud, and
ToussANT. Revised and Edited by M. F. Malpeyre.
Translated from the French by A. A. Fesquet. Illustrated
by Eighty Engravings. 659 pp. 8 vo $5.00-
ROPER. — Catechism for Steam Engineers and Elec-
tricians:
Including the Construction and Management of Steam En-
gines, Steam Boilers and Electric Plants. By Stephen
Roper. Twenty-first edition, rewritten and greatly enlarged
by E. R. Keller and C. W. Pike. 365 pages. Illustrations.
l8mo., tucks, gilt $2.00
HENRY CAREY BAIRD & CO.'S CATALOGUE 21
ROPER.— Engineer's Handy Book:
Containing Facts, Formulae, Tables and Questions on Power,
its Generation, Transmission and Measurement; Heat, Fuel,
and Steam; The Steam Boiler and Accessories; Steam Engines
and their Parts; Steam Engine Indicator; Gas and Gasoline
Engines; Materials; their Properties and Strength; Together
with a Discussion of the Fundamental Experiments in Elec-
tricity, and an Explanation of Dynamos, Motors, Batteries,
etc., and Rules for Calculating Sizes of Wires. By Stephen
Roper. 15th edition. Revised and enlarged by E. R.
Keller, M. E., and C. W. Pike, B. S. With numerous
illustrations. Pocket-book form. Leather $3-50
ROPER. — Hand-Book of Land and Marine Engines:
Including the Modeling, Construction, Running, and Manage-
ment of Land and Marine Engines and Boilers. With illu-
strations. By Stephen Roper, Engineer. Sixth edition.
i2mo., tucks, gilt edge $3-5o
ROPER.— Hand-Book of the Locomotive:
Including the Construction of Engines and Boilers, and the
Construction, Management, and Running of Locomotives.
By Stephen Roper. Eleventh edition. i8mo., tucks, gilt
edge $2.50,
ROPER. — Hand-Book of Modern Steam Fire-Engines:
With illustrations. By Stephen Roper, Engineer. Fourth
edition, i2mo., tucks, gilt edge fe.50
ROPER.— Instructions and Suggestions for Engineers and
Firemen :
By Stephen Roper, Engineer. i8mo., Morocco $2.00
ROPER. — Questions and Answers for Stationary and
Marine Engineers and Electricians:
With a Chapter of What to Do in Case of Accidents. By
Stephen Roper, Engineer. Sixth edition. Rewritten and
Greatly fenlarged by Edwin R. Keller, M. E., and Clayton
W. Pike, B. A. 306 pp. Morocco, pocketbook form, gilt
edges $^-0o
ROPER.— The Steam Boiler: Its Care and Management:
By Stephen Roper, Engineer. i2mo.,tuck, gilt edges. $2.00
ROPER. — Use and Abuse of the Steam Boiler:
By Stephen Roper, Engineer. Ninth Edition, with illus-
trations. i8mo., tucks, gilt edge $2.00 ,
ROPER.— The Young Engineer's Own Book:
Containing an Explanation of the Principle and Theories on
which the Steam Engine as a Prime Mover is based. By
Stephen Roper, Engineer. 160 Illustrations,' 363 pages.
i8mo., tuck • $2.50
22 HENRY CAREY BAIRD & CO.'S CATALOGUE
ROSE.— The Complete Practical Machinist:
Embracing Lathe Work, Vise Work, Drills and Drilling, Taps
and Dies, Hardening and Tempering, the Making and Use of
Tools, Tool Grinding, Marking out work. Machine Tools, etc.
By Joshua Rose. 395 Engravings. Nineteenth Edition,
greatly Enlarged with New and Valuable Matter. i2mo.,
504 pages I2.50
ROSE.— Mechanical Drawing Self-Taught:
Comprising Instructions in the Selection and Preparation of
Drawing Instruments, Elementary Instruction in practical
Mechanical Drawing, together with Examples in Simple
Geometry and Elementary Mechanism, including Screw
Threads, Gear Wheels, Mechanical Motions, Engines and
Boilers. By Joshua Rose, M. E. Illustrated by 330 en-
gravings. 8vo. 313 pages $3.50
ROSE.— The Slide- Valve Practically Explained:
Embracing simple and complete Practical Demonstrations of
the operation of each element in a Slide-valve Movement,
and illustrating the effects of Variations in their Proportions
by examples carefully selected from the most recent and
successful practice. By Joshua Rose, M. E. Illustrated
by 35 engravings jSl.oo
ROSE.— Steam Boilers:
A Practical Treatise on Boiler Construction and Examination,
for the Use of Practical Boiler Makers, Boiler Users, and In-
spectors; and embracing in plain figures all the calculations
necessary in Designing or Classifying Steam Boilers. By
Joshua Rose, M. E. Illustrated by 73 engravings. 250
pages. 8vo $2.00
ROSS. — The Blowpipe in Chemistry, Mineralogy and
Geology:
Containing all Known Methods of Anhydrous Analysis, many
Working Examples, and Instructions for Making Apparatus.
By Lieut. Colonel W. A. Ross, R. A., F. G. S. With 120
Illustrations. l2mo $2.00
SCHRIBER.— The Complete Carriage and Wagon Painter:
A Concise Compendiun of the Art of Painting Carriages,
Wagons, and Sleighs, embracing Full Directions in all the
Various Branches, including Lettering, Scrolling, Ornamenting,
Striping, Varnishing, and Coloring, with numerous Recipes
for Mixing Colors. 73 illustrations. 177 pp. l2mo. ..$1.00
SHAW.— Civil Architecture:
Being a Complete Theoretical and Practical System of Build-
ng, containing the Fundamental Principles of the Art. By
Edward Shaw, Architect. To which is added a Treatise on
HENRY CAREY BAIRD & CO.'S CATALOGUE 23
Gothic Architecture, etc. By Thomas W. Silloway and
George M. Harding, Architects. The whole illustrated bj'
102 quarto plates finely engraved on copper. Eleventh edi-
tion. 4to §5.00
SHERRATT.— The Elements of Hand-Railing:
Simplified and Explained in Concise Problems that are Easily
Understood. The whole illustrated with Thirty-eight Ac-
curate and Original Plates, Founded on Geometrical Principles,
and showing how to Make Rail Without Centre Joints, Making
Better Rail of the Same Material, with Half the Labor, and
Showing How to Lay Out Stairs of all Kinds. By R. J.
Sherratt. Folio $2.50
SHUNK.^ — A Practical Treatise on Railway Curves and
Location, for Young Engineers:
By W. F. Shunk, C. E. l2mo. Full bound pocket-book
form ?2.oo
SLOANE. — Home Experiments in Science:
By T. O'CONOR Sloane, E. M., A. M., Ph.D. Illustrated by
gi engravings. i2mo Si.oo
SLOAN. — Homestead Architecture:
Containing Forty Designs for Villas, Cottages, and Farm-
houses, with Essays on Style, Construction, Landscape Gar-
dening, Furniture, etc., etc. Illustrated by upwards of 200
engravings. By Samuel Sloan, Architect. 8vo $2.00
SMITH.— The Dyer's Instructor:
Comprising Practical Instructions in the Art of Dyeing Silk,
Cotton, Wool, and Worsted, and Woolen Goods; containing
nearly 800 Receipts. To which is added a Treatise on the
Art of Padding; and the Printing of Silk Warps, Skeins, and
Handkerchiefs, and the various Mordants and Colors for
the different styles of such work. By David Smith, Pattern
Dyer. i2mo. $1.00
SMITH. — A Manual of Political Economy:
By E. Peshine Smith. A New Edition, to which is added a
full Index. l2mo $1.25
SMITH. — Parks and Pleasure-Grounds:
Or Practical Notes on Country Residences, Villas, Public
Parks, and Gardens. By Chari.es H. J. Smith, Landscape
Gardener and Garden Architect, etc., etc. l2mo $2.00
SNIVELY.— The Elements of Systematic Qualitative
Chemical Analysis:
A Hand-book for Beginners. By John H. Snively, Phr. D.
l6mo $2.00
24 HENRY CAREY BAIRD & CO.'S CATALOGUE
STOKES.— The Cabinet Maker and Upholsterer's Com-
panion :
Comprising the Art of Drawing, as applicable to Cabinet
Work; Veneering, Inlaying, and Buhl- Work; the Art of Dye-
ing and Staining Wood, Ivory, Bone, Tortoise-Shell, etc.
Directions for Lacquering, Japanning, and Varnishing; to
make French Polish, Glues, Cements, and Compositions;
with numerous Receipts, useful to workmen generally. By
J. Stokes. Illustrated. A New Edition, with an Appendix
upon French Polishing, Staining, Imitating, Varnishing, etc.,
etc. l2rao jfl.zs
STRENGTH AND OTHER PROPERTIES OF METALS:
Reports of Experiments on the Strength and other Properties
of Metals for Cannon. With a Description of the Machines
for Testing Metals, and of the Classification of Cannon in
service. By Officers of the Ordnance Department, U. S.
Army. By authority of the Secretary of War. Illustrated
by 25 large steel plates. Quarto fe.oo
SULZ. — A Treatise on Beverages:
Or the Complete Practical Bottler. Full Instructions for
Laboratory Work with Original Practical Recipes for all
kinds of Carbonated Drinks, Mineral Waters, Flavoring
Extracts, Syrups, etc. By Charles Herman Sulz, Technical
Chemist and Practical Bottler. Illustrated by 428 Engrav-
ings. 818 pp. 8vo I7.50
SYME.^Outlines of an Industrial Science:
By David Syme. i2mo JS2.00
TABLES SHOWING THE WEIGHT OF ROUND, SQUARE
AND FLAT BAR IRON, STEEL, ETC.
By Measurement. Cloth 63
TEMPLETON.— The Practical Examinator on Steam and
the Steam-Engine.
With Instructive References relative thereto, arranged for
the Use of Engineers, Students, and others. By William
Templeton, Engineer. i2mo $1.00
THALLNER.— Tool-Steel :
A Concise Hand-book on Tool-Steel in General. Its Treat-
ment in the Operations of Forging, Annealing, Hardening,
Tempering, etc., and the Appliances Therefor. By Otto
Thallner, Manager in Chief of the Tool-Steel Works, Bis-
marckhiitte, Germany. From the German by William T.
Brannt. Illustrated by 69 engravings. 194 pages. 8vo.
1902 $2.00
THAUSING.— The Theory and Practice of the Preparation
of Malt and the Fabrication of Beer:
With especial reference to the Vienna Process of Brewing.
HENRY CAREY BAIRD & CO.'S CATALOGUE 25
Elaborated from personal experience by Julius E. Thausing,
Professor at the School for Brewers, and at the Agricultural
Institute, Modling, near Vienna. Translated from the Ger-
man by William T. Brannt. Thoroughly and elaborately
edited, with much American matter, and according to the
latest and most Scientific Practice, by A. Schwarz and Dr.
A. H. Bauer. Illustrated by 140 Engravings. 8vo. 815
pages $10.00
TOMPKINS.— Cotton and Cotton Oil:
Cotton: Planting, Cultivating, Harvesting and Preparation
for Market. Cotton Seed Oil Mills: Organization, Construc-
tion and Operation. Cattle Feeding: Production of Beef
and Dairy Products, Cotton Seed Meal and Hulls as Stock
Feed. Fertilizers: Manufacture, Manipulation and Uses.
By D. A. Tompkins. 8vo. 494 pp. Illustrated I7.50
TOMPKINS.— Cotton Mill, Commercial Features:
A Text-Book for the Use of Textile Schools and Investors.
With Tables showing Cost of Machinery and Equipments
for Mills making Cotton Yarns and Plain Cotton Cloths. By
D. A. Tompkins. 8vo. 240 pp. Illustrated fS-oo.
TOMPKINS.— Cotton Mill Processes and Calculations:
An Elementary Text-Book for the Use of Textile Schools and
for Home Study. By D. A. Tompkins. 312 pp. 8vo.
Illustrated $5.00
TURNER'S (THE) COMPANION:
Containing Instructions in Concentric, Elliptic, and Eccen-
tric Turning; also various Plates of Chucks, Tools, and In-
struments; and Directions for using the Eccentric Cutter,
Drill, Vertical Cutter, and Circular Rest; with Patterns and
Instructions for working them. l2mo $1.00
VAN CLEVE.— The English and American Mechanic:
Comprising a Collection of Over Three Thousand Receipts,
Rules, and Tables, designed for the Use of every Mechanic
and Manufacturer. By B. Frank Van Cleve. Illustrated.
500 pp. l2mo $2.00
VAN DER BURG.— School of Painting for the Imitation
of Woods and Marbles:
A Complete, Practical Treatise on the Art and Craft of Grain-
ing and Marbling with the Tools and Appliances. 36 plates.
Folio, 12x20 inches $6.00.
VILLE. — ^The School of Chemical Manures:
Or, Elementary Principles in the Use of Fertilizing Agents.
From the French of M. Geo. Ville, by A. A. Fesquet,
Chemist and Engineer. With Illustrations. i2mo. ...$1.25
26 HENRY CAREY BAIRD & CO.'S CATALOGUE
VOGDES.— The Architect's and Builder's Pocket-Com-
panion and Price- Book:
Consisting of a Short but Comprehensive Epitome of Deci-
mals, Duodecimals, Geometry and Mensuration; with Tables
of United States Measures, Sizes, Weights, Strengths, etc., of
Iron, Wood, Stone, Brick, Cement and Concretes, Quanti-
ties of Materials in given Sizes and Dimensions of Wood,
Brick and Stone; and full and complete Bills of Prices for
Carpenter's Work and Painting; also, Rules for Computing
and Valuing Brick and Brick Work, Stone Work, Painting,
Plastering, with a Vocabulary of Technical Terms, etc. By
Frank W. Vogdes, Architect, Indianapolis, Ind. Enlarged,
revised, and corrected. In one volume, 368 pages, full-bound,
pocketbook form, gilt edges $2.00
Cloth $1.50
WAHNSCHAFFE.— A Guide to the Scientific Examina-
tion of Soils:
Comprising Select Methods of Mechanical and Chemical
Analysis and Physical Investigation. Translated from the
German of Dr. F. Wahnschaffe. With additions by Wil-
liam T. Brannt. Illustrated by 25 engravings. i2mo.
177 pages $1.50
WARE.— The Sugar Beet:
Including a History of the Beet Sugar Industry in Europe,
Varieties of the Sugar Beet, Examination, Soils, Tillage,
Seeds and Sowing, Yield and Cost of Cultivation, Harvesting,
Transportation, Conservation, Feeding Qualities of the Beet
and of the Pulp, etc. By Lewis S. Ware, C. E., M. E.
Illustrated by ninety engravings. 8vo $2.00
WARN.— The Sheet-Metal Worker's Instructor:
For Zinc, Sheet-Iron, Copper, and Tin-Plate Workers, etc.
Containing a selection of Geometrical Problems; also, Prac-
tical and Simple Rules for Describing the various Patterns
required in the different branches of the above Trades. By
Reuben H. Warn, Practical Tin-Plate Worker. To which is
added an Appendix, containing Instructions for Boiler-Mak-
ing, Mensuration of Surfaces and Solids, Rules for Cal-
culating the Weights of different Figures of Iron and Steel,
Tables of the Weights of Iron, Steel, etc. Illustrated by
thirty-two Plates and thirty-seven Wood Engravings. 8vo.
$2.00
WARNER. — New Theorems, Tables, and Diagrams, for
the Computation of Earth- work:
Designed for the use of Engineers in Preliminary and Final
Estimates, of Students in Engineering and of Contractors
and other non-professional Computers. In two parts, with
an Appendix. Part I. A Practical Treatise; Part II. A
HENRY CAREY BAIRD & CO.'S CATALOGUE 27
Theoretical Treatise, and the Appendix Containing Notes to
the Rules and Examples of Part I.; Explanations of the Con-
struction of Scales, Tables, and Diagrams, and a Treatise
upon Equivalent Square Bases and Equivalent Level Heights.
By John Warner, A. M., Mining and Mechanical Engineer.
Illustrated by 14 Plates. 8vo $3.00
WATSON.— A Manual of the Hand-Lathe:
Comprising Concise Directions for Working Metals of all
kinds. Ivory, Bone, and Precious Woods; Dyeing, Coloring,
and French Polishing; Inlaying by Veneers, and various
methods practised to produce Elaborate work with dispatch,
and at Small Expense. By Egbert P. Watson, Author of
"The Modern Practice of American Machinists and En-
gineers." Illustrated by 78 engravings §1.00
WATSON. — ^The Modern Practice of American Machinists
and Engineers:
Including the Construction, Application, and Use of Drills,
Lathe Tools, Cutters for Boring Cylinders, and Hollow-work
generally, with the most economical Speed for the same; the
Results verified by Actual Practice at the Lathe, the Vise,
and on the floor. Together with Workshop Management,
Economy of Manufacture, the Steam Engine, Boilers, Gears,
Belting, etc., etc. By Egbert P. Watson. Illustrated by
eighty-six engravings. i2mo $2.00
WEATHERLY.— Treatise on the Art of Boiling Sugar,
Crystallizing, Lozenge-making, Comfits, Gum Goods:
And other processes for Confectionery, including Methods
for Manufacturing every Description of Raw and Refined
Sugar Goods. A New and Enlarged Edition, with an Appen-
dix on Cocoa, Chocolate, Chocolate Confections, etc. 196
pages. i2mo. (1903-) ?i-50
WILL. — Tables of Qualitative Chemical Analysis:
With an Introductory Chapter on the Course of Analysis.
By Professor Heinrich Will, of Giessen, Germany. Third
American, from the eleventh German edition. Edited by
Charles F. Himes, Ph. D., Professor of Natural Science,
Dickinson College, Carlisle, Pa. 8vo $1.00
WILLIAMS.— On Heat and Steam:
Embracing New- Views of Vaporization, Condensation and
Explosion. By Charles Wye Williams, A. I. C. E. Illus-
trated. Bvo J?2.00
WILSON.— The Practical Tool-Maker and Designer:
A Treatise upon the Designing of Tools and Fixtures for
Machine Tools and Metal Working Machinery, Comprising
Modern Examples of Machines with Fundamental Designs
28 HENRY CAREY BAIRD & CO.S CATALOGUE
for Tools for the Actual Production of the work; Together
with Special Reference to a Set of Tools for Machining the
Various Parts of a Bicycle. Illustrated by 189 engravings
(1898.) JS2.50
CONTENTS: Introductory. Chapter I. Modern Tool Room and
Equipment. II. Files, Their Use and Abuse. III. Steel and Tempering.
IV. Making Jigs. V. Milling Machine Fixtures. VI. Tools and Fixtures
for Screw Machines. VII. Broaching. VIII. Punches and Dies for Cut-
ting and Drop Press. IX. Tools for Hollow- Ware. X. Embossing: Metal.
Coin, and Stamped Sheet-Metal Ornaments. XI. Drop Forging. XII.
Solid Drawn Shells or Ferrules; Cupping or Cutting, and Drawing; Break-
ing Down Shells. XIII. Annealing, Pickling, and Cleaning. XIV. Tools
for Draw Bench. XV. Cutting and Assembling Pieces by Means of Rat-
chet Dial Plates at One Operation. XVI. The Header. XVII. Tools for
Fox Lathe. XVIII. Suggestions for a set of Tools for Machining the
Various Parts of a Bicycle. XIX. The Plater's Dynamo. XX. Conclu-
sion— With a Few Random Ideas. Appendix. Index.
BRANNT'S "SOAP MAKER'S HAND BOOK."
The most helpful and up-to-date book on the Art of Soap
Making in the English language.
In one volume, 8vo, B35 pages, illustrated by 54: engravings.
Price $6,00 net. Free of Postage to any Address in the World,
or by Express C. O. D. freight paid to any Address in the
United States or Canada.
PUBLISHED APRIL, 1912.
THE
SOAP MAKER'S HAID BOOK
OF
MATERIALS, PROCESSES AND RECEIPTS FOR
EVERY DESCRIPTION OF SOAP
ijroLnDiNo
PATS, PAT OILS, AND PATTY ACIDS ; EXAMINATION OP PATS AND OILS ;
ALKALIES ; TESTING SODA AND POTASH ; MACHINES AND UTENSILS ;
HARD SOAPS ; SOPT SOAPS ; TEXTILE SOAPS ; WASHING POWDERS
AND ALLIED PEODUOTS ; TOILET SOAPS, MEDICATED SOAPS,
AND SOAP SPECIALTIES ; ESSENTIAL OILS AND OTHER
PERFUMING MATERIALS ; TESTING SOAPS.
EDITED CHIEFLY FROM THE GERMAN OF
DR. C. DEITE, A. ENGELHARDT, F. WILTNER,
AND NUMEROUS OTHER EXPERTS.
WITH ADDITIONS
BY
WILLIAM T. BRANNT,
EDITOK OP "THK TECHNO CHEMICAL EEOEIPT BOOK."
(LLUSTRATED BY FIPTT-FOUR ENGFIA.VINGS.
SECOND EDITION. REVISED AND IN GREAT PART RE-WRITTEN.
PHILADELPHIA :
HENRY CAREY BAIRD & CO.,
INDUSTRIAL PUBLISHEES, BOOKSELLERS AND IMPORTERS,
810 Walnut Street.
1911
KIRK'S CUPOLA FURNACE.
An Eminently, Practical, Up-to-Date Booh, by an Expert.
Third Thoroughly Revised and Partly Re-written Edition.
In one volume, 8vo,, 4:82 pages, illustrated by one hundred
and six engravings. Price $8.30. Free of Postage to any
Address in the World, or by Express C. O. D., freight paid to
any Address in the United States or Canada.
PUBLISHED AUGUST, 1910.
THE CUPOLA FURNACE
A PRACTICAL TREATISE ON THE
CONSTRUCTION AND MANAGEMENT
OF
FOUNDRY CUPOLAS:
COMPRISING
IMPROVEMENTS IN CUPOLAS AND METHODS OF THEIR CONSTRUCTION AND MANAGE-
MENT; TUYERES; MODERN CUPOLAS; CUPOLA FUELS; FLUXING OF IRON; GETTING
UP CUPOLA STOCK; RUNNING A CONTINUOUS STREAM; SCIENTIFICALLY
DESIGNED CUPOLAS; SPARK-CATCIIING DEVICES; BLAST-PIPES AND
BLAST; BLOWERS; FOUNDRY TRAM RAIL, ETC, ETC.
BY
EDWARD KIRK,
PRACTICAL MOULDER AND MELTER, CONSULTING EXPERT IN MELTING.
Author of " The Founding of Meials^^ and o/Kumero2tc Papers on Cupola Practice,
ILLUSTRATED BY ONE HUNDRED AND SIX ENGRAVINGS.
THIRD THOROUGHLY REVISED AND PARTLY RE-WR.TTEN EDITION.
PHILADELPHIA :
HENRY CARIDY BAIRD & CO.,
INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS,
810 Walnut Stbeet.
KIRK'S FOUNDRY IRONS.
A Practical, JTp-to-Date Book, by the well known Eoapert.
In one volume, 8vo, 294: pages, illustrated. Price $3.00 net.
Free of Postage to any Address in the World, or by Express
C. O. D., freight paid to any Address in the United States or
Canada.
PUBLISHED JUNE, 1911.
A PRACTICAL TREATISE
ON
FOUNDRY IRONS
COMPRISING
PIG IRON, AND FRACTURE GRADING OF PIG AND SCRAP IRONS ;
SCRAP IRONS ; MIXING IRONS ; ELEMENTS AND METALLOIDS ;
GRADING IRON BY ANALYSIS ; CHEMICAL STANDARDS
FOR IRON CASTINGS ; TESTING CAST IRON ; SEMI-
STEEL ; MALLEABLE IRON ; ETC. , ETC.
BY
EDWARD KIRK,
PRACTICAL MOULDER AND MELTER; CONSULTING F.XPERT IN MELTING.
AUTHOR OF "the CUPOLA FURNACE," AND OF NUMEROUS
PAPERS ON CUPOLA PRACTICE.
ILLUSTRATED
PHILADELPHIA :
HENRY CAREY BAIRD & CO.,
INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS,
810 Walnut Street.
1911
BRANNT'S DRY GLEANER.
The only book, including Mat Cleaning and Reno-
vating in any language, in one volume, 12nio, S71
pages, illustrated. Price $2.60 net, Free of postage
to any address in the world, or by express freight
paid to any address in the United States or Canada,
PUBLISHED OCTOBER, 1911.
THE PRACTICAL
DRY CLEANER, SCOURER, AND
GARMENT DYER:
COMPRISING
DRY, CHEMICAL, OR FRENCH CLEANING; PURIFICATION OF BENZINE;
REMOVAL OF STAINS, OR SPOTTING; WET CLEANING; FINISHING
CLEANED FABRICS ; CLEANING AND DYEING FURS, SKIN RUGS
AND mats; CLEANING and DYEING FEATHERS; CLEANING
AND RENOVATING FELT, STRAW AND PANAMA HATS;
BLEACHING AND DVEING STRAW AND STRAW HATS;
CLEANING AND DVEING GLOVES; GARMENT
DYEING; STRIPPING; ANALYSIS OF
TEXTILE FABRICS.
EDITED BY
WILLIAM T. BRANNT,
EDITOR OF "the TECHNO-CHEMICAL RECEIPT BOOK,"
FOURTH EDITION, REVISED AND ENLARGED.
ILLUSTRATED BY FORTY-ONE ENGRAVINGS.
PHILADELPHIA:
HENRY CAREY BAIRD & CO.,
INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS,
810 WALNUT STREET.
1911.